The best answers address the question directly, and back up facts with wikilinks and links to sources. Do not edit others' comments and do not give any medical or legal advice.
The Scientific American website currently has a news story [1] about a fire suppression "grenade" which uses potassium carbonate as its active ingredient to suppress fire "at the molecular level". It appears that potassium carbonate/potassium bicarbonate is a common ingredient in fire extinguishers (e.g Purple-K). However, none of those pages mention how it works, except for Purple-K saying it "directly inhibit[s] the chemical chain reaction", with the CO2 smothering being relegated to a minor role (as expected, since potassium chloride also works in fire suppression). - So what is the mechanism for potassium (bi)carbonate fire suppression? -- 128.104.112.147 (talk) 00:19, 6 September 2008 (UTC)[reply]
I'm pretty sure I sure something on one of Adam Hart-Davies's shows, where he demonstrated glass fire extinguishers (probably Victorian era). They were roughly grenade shaped and sized, and contained bicarbonate of something. DuncanHill (talk) 09:48, 6 September 2008 (UTC)[reply]
Those links don't exactly answer my question. The article potassium chloride (KCl), notes that it works as a fire extinguishing agent, but obviously doesn't have any CO2 or H2O to release. HowStuffWorks is claiming that dry chemical fire extinguishers work by smothering the fire by coating the fuel with an "inert solid (similar to dirt or sand)". However, the article Purple-K notes that "Dry Chemical Powder works by directly inhibiting the chemical chain reaction" (the bottom of the fire tetrahedron, versus the oxygen leg of the fire triangle, as implied by HowStuffWorks). The article potassium carbonate notes that aqueous potassium carbonate is used for restaurant fires - so it's not just water release (as they'd use just water), and it isn't smothering with an inert solid (as the dissolved carbonate isn't a solid). - So to clarify my question, I'm looking for confirmation if there is some sort of chemical (versus physical) mechanism of action in potassium/sodium bicarbonate/carbonate/chloride fire suppression, and if so, what the chemical mechanism is. -- 128.104.112.147 (talk) 19:38, 6 September 2008 (UTC)[reply]
Both birds are the same sex and age. Both are descended from many tens of generations of captive-bred stock. Both have been parent raised and kept in an aviary with others of their own kind for their whole lives. A lives in England. B lives in China.
Now suppose that A and B were to be introduced to each other in aviary conditions. Would they be able to communicate and interact with each other in the same way as two wild Cockatiels of the same age and sex from roughly the same area in their natural habitat would - or would there be a significant 'language gap'? --Kurt Shaped Box (talk) 01:23, 6 September 2008 (UTC)[reply]
Good question, and I can only imagine they could at least communicate basically. After years of separation in the New World, Americans simply developed a different language from their English ancestors, they don't speak a strange unrelated language called American. Further, any normal bird doesn't answer direct commands like a dog - "sit, fly" etc. Unless, like a parrot, it learns to talk, it's Chinese speaking owners are hardly going to morph it into a different "bird language." Unfortunately it would take a long time to find out, though.78.144.137.205 (talk) 08:51, 6 September 2008 (UTC)[reply]
If they wanted to sit around and discuss the current political situation then clearly they would need a common language. But what sort of communication are we talking about. I have never kept these birds but most of their communication is about posture, eye contact, squawking, pecking and scratching. Wouldn't all of that stuff be genetically hard-wired? If you went to a country where you spoke not a syllable of the language I'll bet you could communicate quite a lot without speaking - facial expressions for starters. A smile is a smile and a frown is a frown wherever you go in the world. When you start using language that moves the personal interface (can I say that?) to a higher plane, one not necessarily available to even sibling cockatiels. Richard Avery (talk) 10:17, 6 September 2008 (UTC)[reply]
There are really four possibilities here:
That parrots learn "language" (or body language or whatever) from their parents. In which case, in your thought experiment, it's likely that the chinese birds would have gradually drifted from the original language - but would that be enough so they couldn't communicate? Who knows? However, you could test this hypothesis with a bird raised entirely by humans who could not have learned from a parent bird and in just one generation would have entirely lost the ability to communicate with others of its species.
That parrots have language built in at the genetic level as an "instinct" - and therefore all parrots, no matter how they are raised can communicate.
That language is genetic - but that the evolutionary/genetic "drift" would be so rapid that our chinese birds would be unable to understand their English counterparts. This seems unlikely.
That parrots don't really communicate with each other much at all making the question entirely moot.
It seems to me that (1) and (4) should be easy to test. If you can eliminate those two then we're down to a genetic/inherited effect - and then if the chinese birds can communicate then it's (2) and if they can't, it's (3).
I presume that such studies have been done for bird-song in general - but perhaps parrots (with their talent of mimicry) are special. That inherent ability to mimic suggests to me that they pick up language from other parrots nearby - so (1) is most likely to be the case and therefore the 'linguistic drift' with the chinese birds may make communication difficult - but perhaps not impossible. But that's entirely supposition based on the idea that mimicry in parrots is there solely to enable them to learn "parrot talk" from their parents and not for some other reason. SteveBaker (talk) 12:25, 6 September 2008 (UTC)[reply]
Thanks for the answers so far, folks. As to Steve's comment - I *think* that the main reasons that parrots 'parrot' is to enable the individuals from a certain flock to communicate with each other more easily over distance, or when aggregating with other flocks. IIRC, each bird copies certain unique elements of the vocalizations from the other birds in the local flock (which consists of relatives and trusted associates - friends, basically) to weave a 'song' (yeah, I know - parrots don't really have what we would call a 'song') that is unique to that flock and is recognized by all other members of the flock as belonging to a bird from that flock. Male birds will also attempt to accurately mimic the calls of females when wooing them, also embellishing the 'song' with sonic elements taken from the surrounding environment - which is apparently seen as a desirable trait in a potential mate (and explains why male companion parrots tend to be be better talkers). Sorry, no refs - this is all 'I read it on the web somewhere' stuff... --Kurt Shaped Box (talk) 15:02, 8 September 2008 (UTC)[reply]
The answer depends on where in the world you live. The solstice occurred at the same absolute instant everywhere inthe world. This was 1990-12-22-0307h UTC, but this was 1990-12-21-2207 EST.-Arch dude (talk) 11:31, 6 September 2008 (UTC)[reply]
Verily. Inhabitants of the northern hemisphere sometimes think their half is the only half worth worrying about, and is therefore for all intents and purposes the entire world. But we southerners know differently. :) -- JackofOz (talk) 14:41, 7 September 2008 (UTC)[reply]
Awwww. I thought it would be cool to have been born on the solstice, but I was born in Massachusetts, where it seems the solstice occurred on the 21st. So I was born on a plain old non-holiday. I don't suppose anything interesting ever happened on the 22nd of December?
And I apologize if I unintentionally insulted anyone south of the equator. I think Australian and New Zealand accents are some of the coolest in the world, if that helps. 128.239.177.28 (talk) 17:03, 7 September 2008 (UTC)Capricorn[reply]
You should read December 22 - that article has a long list of things that happened on that day. In fact, the very day you were born (Dec 22 1990) was "Final independence of the Marshall Islands and Federated States of Micronesia after termination of trusteeship. and you share a birthday with the "famous" French actor Jean-Baptiste Maunier - and you thought nothing interesting happened!...(OK, maybe you have a point!) Hmmm...Disneyland opened on the day I was born! SteveBaker (talk) 18:52, 7 September 2008 (UTC)[reply]
I'm not too sure what "final independence" means (they were free for the last time? so they were taken over immediately after that?)and I'd never heard of the Federated States of Micronesia, though according to its article it's a real place somewhere in Oceania. But thanks anyway! I guess I'll have to start watching more French movies to see Jean-Baptiste Maunier... 128.239.177.28 (talk) 13:53, 8 September 2008 (UTC)Capricorn[reply]
Drugs that daze or slow down?
What category of drug generally slows down your movement or walking speed?
What category of drug drug puts you in a daze, e.g. making you only able to do one thing in the time it would take you to do 2 or 3?
Why is there a specific maximum amount of water vapor that can exist in air at specific temperatures? A similar question would be 'Why is there a dew point temperature for each air temperature?'. I have searched the internet (and Wikipedia of course) and have not been able to pick up this answer.
172.168.186.87 (talk) 03:04, 6 September 2008 (UTC)[reply]
Have you read dew point? It doesn't have a very detailed explanation, but it has a brief one. If you want more than that, you'll have to wait for someone more knowledgeable to come along, I'm afraid. --Tango (talk) 03:12, 6 September 2008 (UTC)[reply]
While that is correct, of course, it's hardly helpful to the OP, I would think. Basically, two forces are at work here: entropy favours all the water molecules to be homogeneously distributed in the form of vapour, while the attractive Van der Waals forces between water molecules favour the water molecules to be close (i.e., favours the liquid form of water). Now, if the certain amount of water in the air exceeds a certain limit (or the temperature drops below the dewpoint), the attractive forces become strong enough to overcome the entropic forces and it becomes energetically favourable for the system to separate into two phases (drops of liquid and the existing vapour). In the liquid fase, the energy of the attractions is low, while in the gaseous state, the entropic contribution to the energy is low, and the fraction of water that condensates will be such that the total energy of the liquids droplets and the vapour together will be lower than the energy of a system where only vapour would be present. --baszoetekouw (talk) 09:40, 6 September 2008 (UTC)[reply]
Here is a really excellent overview of the process, specifically worded to avoid the rather poor metaphors often employed by textbooks. Further on the website here you can find the replies to the protests you'll make after reading the first page. Matt Deres (talk) 01:56, 7 September 2008 (UTC)[reply]
I don't have an answer for what it is, but I think you should be writing to your local trading standards officer as well as the Wikipedia Refdesk. SpinningSpark08:07, 6 September 2008 (UTC)[reply]
Western US, the food is mostly dry goods (flour, noodles, rice, etc.) from the local supermarkets. I'm not sure if they're inside the packages to start from, or if they've taken up residence in my pantry and are eating their way into the packages. I only rarely spot them outside the packaging, and they're invariably dead when I do find them. --Carnildo (talk) 09:16, 6 September 2008 (UTC)[reply]
I think Richard Avery is right. HERE is a link to one common species of Pyralidae. It can get into small spaces and loves grain products. Do you often see small moths flying around in your kitchen?
If these are what you have, the texture of the infested flour (or other finely ground grain) is likely to be unusual, as if it was impregnated with many tiny spider webs. It could be described as "stringy".
If this is what you have, the nontoxic traps mentioned in the article are worth trying. They are made specifically for this pest and can catch hundreds of moths. If you google "pantry moth trap pheromone" you can find more information. My local hardware store sells the traps. Maybe yours does also. Wanderer57 (talk) 17:10, 6 September 2008 (UTC)[reply]
I'd say they're mealworms (I've also seen some bugs that look like the adult beetles in that article), but the larva and adults I've seen are less than half the size mentioned in the article. --Carnildo (talk) 19:17, 6 September 2008 (UTC)[reply]
If I can make a recommendation... we've always found that sealing flour and sugar in large glass containers to be the most effective way of deterring pests of this sort. Boxes and bags just don't cut it. --98.217.8.46 (talk) 18:35, 6 September 2008 (UTC)[reply]
UK Coal Reserves
The table, entitled 'Proved recoverable coal reserves at end-2006 (million tonnes (teragrams))' in the Coal article, under section 'Production Trends', subsection 'World coal reserves', does not include an entry for the United Kingdom. This source states that there are enough 'untapped coal reserves in the UK to last 400 years.' and this source states that there 'are around 250 million tonnes of coal not yet mined in South Wales' (obviously this excludes the rest of the UK). My question is: Is the table incomplete, are the two BBC reports incorrect, or is there another explanation? I've asked this question on the Coal article talk page, but haven't received a response. Thanks, Daicaregos (talk) 08:24, 6 September 2008 (UTC)[reply]
The source for that table has the UK with only 220 million tonnes, which is less than 0.05% of the world total, so wasn't included in our table. The source says that it only includes reserves that are known to be extractable under "existing economic and operating conditions", so perhaps they didn't include all the coal mines in the UK that have been closed with coal still in them. Seems an odd decision - they can be re-opened pretty easily if the need arises. --Tango (talk) 08:06, 6 September 2008 (UTC)[reply]
Thanks for your reply, Tango. That makes sense (why it's not on the table). Perhaps the discrepancy between your source and the BBC/Media Wales sources will disappear when they next update their table. We'll see. In the meantime I'll update the United Kingdom, economy section to read reserves of at least 220 million tonnes (It currently says 'The UK has a small coal reserve'. 220 million tonnes doen't seem that small to me though). Would you mind posting the link to the reference please, so I can quote it? Cheers :) Daicaregos (talk) 08:24, 6 September 2008 (UTC)[reply]
As usual - let's crunch the numbers guys: Fossil fuel power plant says that a typical coal-fired power station uses 10,000 tons of coal per day. (1 tonne == 1.1 ton) So 220 million tonnes (240 million tons) is only enough to run one "typical" power plant for 24,000 days - about 70 years...or 70 power plants for one year. I'm fairly sure there are more than 70 coal-fired power stations of "typical" size in the UK. So 220 million tonnes is NOTHING...not even a year's supply for the UK. That's hardly a significant reserve - in fact it's such an utterly trivial amount as to be essentially negligable - and it certainly doesn't come close to explaining the "400 years" figure. (And this assumes that no coal is used in other industrial uses - such as coke production - which is needed for steel making and other industrial activities) SteveBaker (talk) 12:09, 6 September 2008 (UTC)[reply]
According to one of the tables at [3], Britain uses about 50 Megatonnes of coal a year in electricity generation. I am still digginf for information on the UK's coal reserves, but it should be noted that they declined sharply after the Conservative government's pit closures of the 80s of last century. This is because reserves are usually quoted of coal which is both technically and economically recoverable. The costs of reopening a deep mine are massive (dewatering, propping, ventilation etc), so while the coal may be there, at current prices it isn't worth getting it out. DuncanHill (talk) 12:24, 6 September 2008 (UTC)[reply]
This last paper says 'The volumes represent 200 years based on the current UK coal consumption of 64 mt p.a.'. Is this paper correct/worth quoting? Or do you guys think I should just leave the United Kingdom, economy section to people who actually know what they're talking about? Daicaregos (talk) 18:48, 6 September 2008 (UTC)[reply]
I think the paper is worth using, (it is from the UK Coal Authority), but do be careful about which of the estimates you use from it, and how you introduce them, as the assumptions on which they are based are important for an understanding of them. DuncanHill (talk) 18:54, 6 September 2008 (UTC)[reply]
Well DuncanHill, would you care to make the amendment to the United Kingdom article, Economy section? You seem to know what you're talking about, and we both know that I don't. I only knew that it wasn't right. How about it? :) Daicaregos (talk) 19:27, 6 September 2008 (UTC)[reply]
I heard of an unusual feature where some people's body temperatures are higher than average, at about 100-102 degrees Fahrenheit. Is this condition real and is there a name for it if so?CalamusFortis15:14, 6 September 2008 (UTC)[reply]
That's a start, but not quite the answer I wanted. The condition of higher than average body temperature occurs all the time. The person's body temperature is normally about 100-102 degrees Fahrenheit, not because the person absorbs too much heat but because his or her body temperature is naturally regulated at 100-102. Is it a symptom of hyperthyroidism?CalamusFortis17:56, 6 September 2008 (UTC)[reply]
There is significant variation of "normal" body temperature between different people - and technically, half of all people in the world have higher than average body temperature while the other half have lower than average. It varies throughout the day and for women, throughout their menstrual cycle. Our pyrexia article says that normal body temperature varies between individuals by about 1 degree F - so someone who is up at 102 is definitely not considered "normal". This makes me suspect that the condition is not in fact "real". The hypothalamus is responsible for temperature regulation. I don't see a name for this problem though...the names seem to relate to the specific causes of elevated temperature. SteveBaker (talk) 18:21, 6 September 2008 (UTC)[reply]
If by "all the time" the OP means that this is a common condition, then I would want to see a WP:RS; if "all the time" in rare individuals is meant, then that is more likely. In addition to the work of Phil Mackowiak, my comment is based on personal experience having looking at daily temp curves in thousands of inpatient adults over the past 20 years. There is a distribution in average temperatures in persons without overt infection, but it's a pretty narrow distribution and many of those with higher temperatures are subsequently found to have occult disease conditions. Scray (talk) 19:38, 6 September 2008 (UTC)[reply]
I should have clarified. What I meant by "all the time" is that the small number of people who have the condition have their temperatures elevated permanently because their bodies maintain their temperatures that high.CalamusFortis23:05, 6 September 2008 (UTC)[reply]
Crystal Filter and Clocks
Are the crystals in the crystal filter same as crystals used oscillator circuits?
Can some one direct me to good resource which has details on how Tx and Rx synchronize their clocks.(wireless n/w).
Suppose I am using two crystals of same frequency from the same manufacturer and using them in Tx and Rx circuits as clocks(After frequency division from several MHz to say 3 or 4kHz)(No temeperature oven or anything fancy...). Once synchronised, how long will they be in sync(order of magnitude) before requiring resynchronization? Lets say that the the Tx and Rx are in the same house or within 20 to 30 metres of each other so that their environment is essentially the same...
3:you may be able to get a one part per million match in the frequency. Then at 4kHz it would take 250 seconds to drift one cycle. Even in the same house you cannot expect to get identical temperatures. With a good oven you may be able to get 1 in a hundred million stability, and if you need higher periods of coherency with out synchronisation you may wish to use a rubidium frequency reference. Graeme Bartlett (talk) 21:50, 6 September 2008 (UTC)[reply]
and, still on #3, how long will they be "in sync" and how frequently they "require" resynchronisation is a function of your application requirements. They're really never in perfect sync; you have to decide what degree of unsync is acceptable. You take the maximum drift (from the crystal's datasheet), do the calculation that Graeme describes, and then compare that to how out of sync you're willing to be. But in the real world you'll resynchronise more frequently than that, to account for worst-case problems in your syncrhonisation scheme, and (this being engineering) an embarassingly large fudge-factor to boot (for all the stuff you don't know to take into account). -- Finlay McWalter | Talk22:06, 6 September 2008 (UTC)[reply]
I'm not sure what the application is here - but generally, in any data transmission system, you use the crystal in the receiver to get you CLOSE to the transmitter's frequency, then use a Phase locked loop to lock into the precise frequency of the transmitter. SteveBaker (talk) 21:58, 6 September 2008 (UTC)[reply]
To Steve- The application is that I'm trying to make (as a part of a project) a serial digital wireless transmission system without using custom chips; as I will not learn anything new if those chips do all the work. So I'll try to use only basic stuff like counters, freq dividers, PLLs, decoders, MUXs, DEMUXs etc... Its reinventing the wheel, and may be too advanced or complicated for me...
Well, I'm not sure I want to lock to the carrier itself. Say I'm plannig to use ASK i.e. switching on and off the carrier according to the ones and zeroes; So i want to sync with the switching frequency (bit_rate^-1). If the switching time is a factor of the carrier frequency (i.e if a bit takes up integral number of carrier cycles), then I will implement your idea. So synchronization will need to be done only once (neglecting problems).Thanks
One more question: I did some SPICE sims on a (not so well designed) crystal filter. The loss due to that stage was much more than 3dB. In what range do these filter's insertion(?) losses lie generally?
September 7
Why do rockets need to be explosive to reach escape velosity?
Years ago there was a short-lived TV show starring Andy Griffiths ("Salvage 1"). In this show, he was a junk collector of things in Earth orbit and (he hoped) on the moon. One of the unique things about his approach to travelling to outter space was to avoid the current explosive rocket approach and instead used a gradual accelleration approach to achieve orbit. On the surface, this seems to make some sense al a gradually accellerating your car at the intersection rather than doing a "jack rabbit start."
My questions is: what are the physics behind the need for an explosive accelleration to achieve orbit rather than the gradual accelleration premise of this TV show? —Preceding unsigned comment added by 209.161.211.89 (talk) 00:53, 7 September 2008 (UTC)[reply]
It's more efficient. All the time you're moving upwards, rather than being in a stable orbit, you have to burn fuel just to maintain your position (and more to move up). It's best to get into orbit as quickly as possible to minimise the fuel used up in that way. --Tango (talk) 01:17, 7 September 2008 (UTC)[reply]
(edit conflict) Yay, finally one that I can answer. Theoretically speaking, it actually doesn't matter how you approach the task of escaping Earth's gravity, as long as you have a Δv large enough to reach escape velocity. However, the problem is that of all the propulsion technologies out there, chemical rocketry is the only one that has a high-enough specific impulse for a reasonable payload/total mass ratio, a high-enough thrust-to-weight ratio to counter Earth's gravity, and is deemed sufficiently safe to use. We could definitely use nuclear propulsion, but it is socially unacceptable to do so. Titoxd(?!? - cool stuff)01:26, 7 September 2008 (UTC)[reply]
In simple terms, before you reach orbit, you're using fuel to do two things: 1) Maintain your current position above ground, and 2) increase your speed towards orbital velocity. The quicker you get into orbit, the less fuel you need to use for (1), which is why current rockets accelerate so hard. Once you're in orbit, you can use gentler, more fuel-efficient technologies like solar sails and ion drives to move around. --Carnildo (talk) 01:37, 7 September 2008 (UTC)[reply]
Indeed, the most efficient way (in terms of propellant/payload mass ratio) to launch a spacecraft into orbit would be to fire it from a cannon, putting all the acceleration (except for the final orbital insertion burn) at the very start of the climb. In practice, of course, the stress this would subject the launch vehicle (not to mention any passengers or other payload) to would be prohibitive, so our current rockets are essentially a compromise between fuel efficiency and limits of practical construction. —Ilmari Karonen (talk) 01:51, 7 September 2008 (UTC)[reply]
If you were launching from the Moon, where there is no atmosphere, the cannon launch method would work better than on Earth, where if the spacecraft emerged from the muzzle of the gun at orbital velocity near the ground, as in the Jules Verne story [[[From the Earth to the Moon]]] it would decelerate and fall to the ground due to the resistance of the air, if it did not burn up first. It is better to reach high velocity only at an altitude where the air is very thin. I expect that higher G acceleration is more efficient of fuel,except for the burning up in thick atmosphere problem, and the killing the passengers from high G force problem. Rising very slowly would be extremely wasteful of fuel in a rocket. Edison (talk) 04:20, 7 September 2008 (UTC)[reply]
On the Moon, you could launch sideways and go straight into orbit (you would need a circularisation burn at some point) rather than going straight up and then going sideways to enter orbit which you need to do on Earth because of the atmosphere. That's the best way to make use of a cannon style launch (see mass driver). --Tango (talk) 04:49, 7 September 2008 (UTC)[reply]
You don't need to get off the ground with chemical rockets, though. You can use a rocketship/airplane hybrid craft. Using airplane technology while you're still in the atmosphere. The Scaled_Composites_White_Knight carried Spaceship One into the air on conventional jet engines and then dropped it before Spaceship One's rocket engines kicked in. . APL (talk) 16:07, 8 September 2008 (UTC)[reply]
Right. Here is a thought experiment: What would happen if we built a spiral-staircase tall enough to reach geostationary orbit? It would be 165,000 miles tall. We could don our space-suits and walk up it (with frequent stops to catch our breath!)...and with the gentlest of push from the topmost step, we'd be in orbit. No "escape velocity" required - no rockets - nothing. SteveBaker (talk) 17:39, 8 September 2008 (UTC)[reply]
Well, of course you don't need escape velocity if you only want to go into orbit. When you push off the top step you are, however, at orbital velocity for the given altitude, as the tower is rotating with the Earth. But if you built the tower even higher, you could reach escape velocity in the same way -- that is, the escape velocity for the altitude you were at. The concept is called a space elevator, among other names; see that article for a list of them. --Anonymous, 21:43 UTC, September 9, 2008.
Did you look at water treatment? Normally there should be water close to 100%. Some dissolved air and carbon dioxide prevents it having a flat flavour. Usually water will be treated with lime to increase it's pH so that it does not dissolve pipes. Other ingredients like chlorine may kill unwanted lifeforms, but really you want zero of this! In the middle east, salt is added because locals prefer their water to taste salty. Ideal percentages of minerals and contaminants may come down to an economical choice - is it worthwhile to remove the contaminants? Graeme Bartlett (talk) 05:53, 7 September 2008 (UTC)[reply]
The absolutely pure water taps in the chemistry labs at my uni have warnings saying the water is harmful if consumed frequently. I'm not sure of the details, but presumably there is something about the minerals in water that is important. --Tango (talk) 05:57, 7 September 2008 (UTC)[reply]
See Tonicity#Hypotonicity for the general explanation but there might be a specific page with information regarding aqua dest..
/wrt chlorine, you need some means to keep the pipes without microorganisms. That is why you have chlorine in tap water, but I never understood why in the US tap water is chlorinated when you can have clean pipes using ozone. Which is much less toxic and doesn't have any taste. --Ayacop (talk) 10:06, 7 September 2008 (UTC)[reply]
Water purification#Disinfection notes that "the main disadvantages of ozone is that it leaves no disinfectant residual in the water". I know that my local water system aims to leave a set (ppm) level of chlorine at the customer's tap, to ensure that no harmful organisms sneak in between the supply and the consumer. There really isn't a way to guarantee that one of the decades-old pipe somewhere in the supply system doesn't have a pinhole leak, or some dead pocket where bacteria can establish a colony. I've been in small towns in the US where they were confident enough in their system not to use chlorine, but in a city of any size, there is just too many worries not to have some sort of residual disinfectant capability throughout the supply line. -- 128.104.112.147 (talk) 19:03, 7 September 2008 (UTC)[reply]
Hah! Talk about synchronicity. The Sept. 9 question in the New York Times science column q+a is "Is it safe to drink distilled water? Does it leach minerals out of the body?" It's safe, according to "two experts on water quality and nutrition at Cornell". Clarityfiend (talk) 22:32, 9 September 2008 (UTC)[reply]
college student seeking advice
Hello, I am a first year student at Mohawk College enrolled in the social service worker course. My main goal for the future is to become a "family therapist". I have experience dealing with people who suffered from alcohol and drug addiction, and I was able to help them gain some will power and get help for themselves. Ever since then, I have had this sudden urge to help anyone and everyone who struggle in life. When I first applied to Mohawk I was under the impression that once I graduated with a degree in social service worker, it would be much easier to apply and be accepted to a university. After doing some research at different universities surrounding our area, I have been unable to find any course that has any relation to "family therapy". If you have not yet figured out where I am going with this, it is that the "social service worker" title is not going to satisfy me. I want more than that...
If you have any advice, or school suggestions, or course suggestions..PLEEEAAAASE respond ASAP
In Ontario Canada, a Social Worker and a Social Services Worker (though governed by the same College) tend to provide two different services based on their education and experiences. Speaking from personal experience, I would suggest that you complete your SSW and then apply to a university for a Social Work program. In my opinion (having supervised students from there, the WLU has one of the best clinical programs around. Also, remember, the university degree is only the starting point: you will need on-going training for several years to come. I completed my BSW (after my BA) and found that until I had my MSW, my oportunities were limited. I also participated in the Introductory and Advanced levels of Brief Therapy in Toronto - this was the BEST clinical training I have ever had and well worth the money!.
So, be patient and plan carefully. I have been at this for 20 years and still have a ways to go!
Even without addressing the specific combinatoric calculation, we can say that's a very low number, because you've ignored the likelihood of recombination, which occurs, on average, slightly more than once per chromosome pair per meiosis. GIven that recombination can occur at so many different locations, the number of different possible gametes is virtually unlimited. - Nunh-huh12:11, 7 September 2008 (UTC)[reply]
why can I listen to the radio on my computer?
Sometimes I can listen on the speakers of my computer to the radio. The sound is quite faint, but it is clearly a radio emission. I have no special program or hardware for that purpose. Why is that possible? —Preceding unsigned comment added by Mr.K. (talk • contribs) 12:10, 7 September 2008 (UTC)[reply]
Could be a lot of things, more information is needed to answer fully. You don't say whether it is broadcast radio you are hearing or something else. Taxi radios, for instance, are notorious for being badly adjusted and badly shielded and get picked up by all kinds of things. Broadcast transmitters can be a problem if you live near one. Do you get internet from your cable TV company? sometimes cable companies put analogue signals down the same cable and poor filtering and/or earthing could be your problem. Finally, are you sure you have not connected to a radio station with your web browser and just have the volume turned down? SpinningSpark15:06, 7 September 2008 (UTC)[reply]
It's perfectly possible. If the length of the cable is exactly right to make an efficient antenna, then a strong AM radio station can induce enough energy into the wire to be audible through the speaker. I've had it with an MP3 player and a pair of headphones - so it's not just leakage from cable TV. You can probably get rid of it by shortening or lengthening the cable - perhaps by coiling up any unused length. If all else fails, go to your local Radio Shack (or local equivalent) and buy a "Ferrite bead" and thread the cable through it a couple of times - that'll usually fix the problem. (You see quite a few computer-type cables with ferrite beads built into them for this exact reason.) SteveBaker (talk) 18:34, 7 September 2008 (UTC)[reply]
A connection or plug which is not a good solid metal to metal jint, like a loose conection with a bit of corrosion, can easily act as a rectifier, just like a crystal radio or a Coherer. It does not need to be tuned to a particular frequency, but could output the audio of the closest/strongest transmitter through the speaker, with no amplification needed. The distributed capacitance of the wires is enough to create an audio signal with the accidental rectifier of an imperfect metallic junction. I had a stereo speaker once that did this. See also the "foxhole radio" example at [5] on Youtube. Edison (talk) 20:18, 7 September 2008 (UTC)[reply]
Lucille Ball (of "I love Lucy" fame) claimed that she had a loose tooth filling that acted as a radio receiver and resulted in music playing in her head. She claimed (bizarrely) that she had on one occasion picked up the sound of morse code - which eventually turned out to be a Japanese spy's radio transmitter located somewhere close to the LA studio where she was working. SteveBaker (talk) 02:52, 8 September 2008 (UTC)[reply]
Actions of people with mental illnes or people using drugs
Well I don't know about mental illness except that in most cases people with it don't have any new ideas that are worth anything to them or others. The idea that insanity is linked to genius is, in all but a handful of cases, totally false.
As for drugs. When on drugs it is common to think that one is getting a flood of new ideas. But in a more sober light most of these are pretty stupid, unoriginal, and uninspiring. I am dubious of the notion that people on drugs think about the world with any more clarity than those not on drugs. It is certainly true that one gets lots of notions. But most of them really aren't anything worth writing home about. There are of course rare exceptions (e.g. it has been said that Kary Mullis claimed to have been inspired to create PCR while on LSD). --98.217.8.46 (talk) 14:07, 7 September 2008 (UTC)[reply]
I disagree with User:98.217.8.46. People with manic-depressive disorder are notoriously super-creative when they are in a manic phase. Sadly, they pay for it in their depressive periods - but there is no question that some of the greatest minds in history have been manic-depressive. Similarly, people (like myself) with high-functioning Autism or Asperger's have long been known to be unusually creative in the extremely narrow areas that interest them. So there is no doubt that some conditions of "mental illness" are certainly able to cause new ideas that are extremely worthwhile to others. So let's dismiss what 98.217.8.46 said and try to answer the original question.
Some drugs act like natural chemicals that are in the normal brain - things like beta-blockers which are known to improve people's ability to pass exams by calming them down. It's hard to imagine that these wouldn't cause new ideas to form that otherwise would not. Not being a nervous wreck clearly improves thinking ability - which clearly causes new ideas to form. On the other hand, many "recreational" drugs operate by basically trashing your brain - wrecking the delicate neural sheaths and basically "shorting out" your neurons - and (predictably) causing all the things that make people on those drugs seem so stupid or perhaps comical. So it's hard to make a general statement - other than that there are some occasions with some drugs where new ideas might appear that would not otherwise have done so.
I guess the hard part about this question is whether that "takes away the constraints to do something". I don't think that's quite the right reason. Alcohol certainly makes people less inhibited ("takes away constraints") - but lots of drugs and mental illnesses do the complete opposite. My condition (Asperger's syndrome) certainly adds a lot of constraints (inability to handle body language and appropriate eye contact for example) - but on the other hand it removes a constraint that "normal" people have about spending LONG periods of time studying a narrow topic. When I was writing the Wikipedia article about the Mini Moke - I knew relatively little about this rather obscure car - I bought literally every single book ever published about it - I scoured eBay for old car magazines that discussed it - and I basically geeked-out on reading this pile of material - 8 hours a day for an entire week. I know now more about the Mini Moke than almost anyone on the planet! (Trust me - this is not very useful) You'd have gotten bored out of your skull by the end of the first chapter. So my condition resulted in a constraint being removed. But whether that resulted in new ideas is certainly rather debatable. (Well, I did get the new idea that I want to spend $10k importing a rusted out Moke from Australia and spending months fixing it up because they are so amazingly cool...but (for example) my Wife didn't find that idea "useful" - so it hasn't (yet) come to fruition.)
So there is no doubt whatever that some drugs and some mental conditions DO cause new ideas to form - whilst others to the exact opposite. I don't agree with the "why" of it though - and it's certainly not true of all mental conditions or all drugs - so we should be careful not to generalize.
I think the problem here is with the definition of mental illness. Perhaps it is more appropriate to use the word “condition” in cases where there is a possibility of a positive effect. --S.dedalus (talk) 23:18, 7 September 2008 (UTC)[reply]
Well - I don't know - use whatever word you like, it doesn't really change the fact that many people who are practically crippled by their "problem" can also gain huge benefits from it - intellectually. Call it a problem, a condition, and illness, a blessing or a curse...that doesn't really change anything. Personally, if it's something you can cure - it's an illness. You can pretty much cure manic depressive syndrome with drugs - but the cure (for some of those people) is not always something they want. Very few Asperger's people want to be "cured"...I'd certainly resist it very strongly. SteveBaker (talk) 01:32, 8 September 2008 (UTC)[reply]
I'm not very surprised to hear that you have Asperger's, Steve; you have a kind of a pedantic approach to things that I have experienced with others with that condition. (It's probably a pretty useful trait for someone working the Ref Desk, too.) Speaking from my own personal experience, I've had my struggles with depression, and I can certainly attest that the manic phases can be very creative. I've kind of mellowed out over the years, though, mostly by learning to read my own signals and adjusting my behavior and circumstances to avoid high-risk situations that trigger unwanted reactions. (In simple terms, this means that, for example, I try to avoid letting myself get sucked into cycles where I don't sleep nearly enough, if at all, and work for extended periods of time until I crash. It sounds stupidly simple, I know, but it took me a bunch of years to figure that pattern out well enough to anticipate it.)
Anyway, my point is, I do a lot of creative work, and some of it has certainly been produced in the more manic periods of my life. Good work, too. I'm tempted to say that those are exceptionally creative phases, but honestly, I don't know whether that's just a mindset where I work hard and the creativity is so strongly present simply because it's contrasted by periods where there isn't any. These days, when I'm more balanced about that stuff, I don't really feel any less creative. All in all, considering that there have been periods when I've been entirely uninterested in, well, most everything in my life, I'd say that on average, I'm probably getting more done now than before.
To kind of answer the original poster's question, I definitely think that it's possible for one to be very creative when under the influence of drugs or suffering from a mental condition, possibly more so than when one would be otherwise -- but I think it would be a mistake to assume that the drugs or the condition themselves are the cause, rather than a catalyst. -- Captain Disdain (talk) 09:39, 8 September 2008 (UTC)[reply]
Obviously whether mental illness has creativity to it depends on one's definition of mental illness. I wasn't putting Autism or Asperger's in that category; I was thinking of depression and schizophrenia in particular (and I write this as someone who has done a lot of work relating to the history of mental health—for every occasional "genius" who suffers from these particular conditions you have a thousand people who can barely get out of bed, people who in a pre-pharmacological time would have to spend their whole lives in institutions). I suppose the main take-away point here is that one's definitions are rather important. --98.217.8.46 (talk) 13:50, 8 September 2008 (UTC)[reply]
Yes it commes from the greek words xenos (ξένος)-stranger and phobia (Φοβία)-fear. the oxford dictionary contains the word xenophobia and it is the psycological condition of fearing-hating stranges... for example see the rednecks in america!!!
Apparently the second spelling of their family name is incorrect, but I've stumbled upon that spelling many times, especially in Spanish publications. Is it just a bad habit that has become widespread in the Spanish community or am I missing something? --Taraborn (talk) 18:03, 7 September 2008 (UTC)[reply]
I don't know about this particular family, but I'd hesitate to tell other people they can't spell their own names. Spelling is an arbitrary thing; spelling of names from other languages or countries even more so, as Ellis Island can attest. I've seen highly amusing rants about "MacDonald" being the only correct spelling -- odd for a name that began as Mac Dhomhnuill. I'm sure that type of certitude gets all the consideration it deserves from Godfrey James Macdonald of Macdonald, 34th hereditary chief of Clan Donald. --- OtherDave (talk) 19:52, 7 September 2008 (UTC)[reply]
Bernouilli certainly seems to be common, and not just in Spain; Wikipedia has it as a redirect. this errata list shows "Bernouilli" being corrected to "Bernoulli" which, while not definitive, is certainly indicative that it is an error. SpinningSpark20:07, 7 September 2008 (UTC)[reply]
I'd be hesitant to claim something as a definite error for a family whose country has at least four languages and who lived very early on in the emergence of the idea that every word has one correct spelling. Bernoulli is certainly the standard spelling in modern English though. Algebraist00:10, 8 September 2008 (UTC)[reply]
If you're a professional scientist, you're probably laughing right now, but sadly I am but a poor high school student and sig figs are imprinted on us as the universal method of...well, messing up otherwise perfectly functional math. Anyway, I have a quick question regarding sig fig arithmetic:
Suppose you have two numbers of equal orders of magnitude and the same number of sig figs, and you subtract one from the other. How many sig figs does the answer have? For example:
0.125 g - 0.106 g = 0.019 g
Then you go off and use the 0.019 g in other calculations. Do you treat it as 3 sig figs (because the data used to obtain it had 3) or 2 (its face value)? In other words, are sig figs based on the numbers you put in, or the lowest point achieved during calculations? Another example:
What you wrote as an answer is correct. The rule that the answer should have the same amount of SigFigs as the number with the least amount of SigFigs only applies when you are multiplying or dividing. When adding or subtracting, the answer should have the same amount of decimal places as the number with the least amount of decimal places.
So for the first one, the answer is "0.019" and has 2 SigFigs. For the second one, the answer is "0.997" and has 3 SigFigs.
It might be best to thing of it in terms of the size of the possible error. 0.125 means 0.125 +/- 0.0005 and 0.106 means 0.106 +/- 0.0005, so the sum becomes (0.125 +/- 0.0005) - (0.106 +/- 0.0005), the maximum value that could give is 0.1255-0.1055=0.200 and the minimum is 0.1245-0.1065=0.0180, so the answer is 0.019 +/- 0.001. That can't be written in terms of significant figures. If we say "0.019 (2sf)" then we mean 0.019 +/- 0.0005, which is more precise than what we actually have, so that would suggest we need less significant figures, so we try 1sf, which gives 0.02 +/ 0.005, which is less precise that what we actually have. Therefore, the best we can do (if you want to stick with significant figures) is to quote it as "0.02 (1sf)", but you've lost some precision by doing that. To quote it was "0.019 (2sf)" (or, even worse, to 3sf) would be false precision, so you certainly can't do that. If you need a final answer in terms of significant figures, your best option is to do all the calculations using figures as precise as you can and carrying through all the +/- terms as I did above and then round the final answer to the most significant figures you can justify (this will almost always be less than what you started with). --Tango (talk) 00:45, 8 September 2008 (UTC)[reply]
The +/- notation certainly seems like a more accurate way to depict uncertainty, but for now I have to use sig figs. What was confusing me was that 0 in the tenths place - the tenths place was significant in both the input data values, but I guess it sort of drops out when you subtract? FlamingSilmaril (talk) 01:11, 8 September 2008 (UTC)[reply]
If you don't want to go through the hassle of carrying through all the errors, you should at the very least knock one sig fig off the final answer, it's virtually never going to be accurate to the same as you started with (so in your first problem above, state the answer as "0.02 (1sf)" (you don't have to specify the "(1sf)" part, it's implied by the fact that you haven't written any trailing 0's, but it might be best to just to make it clear that it's an approximate answer). The error represented by a given number of significant figures depends on the magnitude of the number, when you subtract two numbers that are close together you get a number with a smaller magnitude, which means the same error is represented by fewer significant figures (however, the actual error is greater than the error you started with, hence the loss of an extra digit). --Tango (talk) 01:23, 8 September 2008 (UTC)[reply]
Just say no to sig.figs. It's useful as a very rough rule to try to avoid quoting more digits of precision in your answer than in your source data. But please - only use that for "back of envelope" calculations. For anything formal - or anytime the answer matters - you have to do as User:Tango says - you have to track the maximum and minimum possible value for every number in your source data and carry that error range through every step of your calculation.
For some bizarre reason, highschool teachers have got it into their heads that the sig.figs thing is a vitally important, cast-iron technique that all scientists use all the time - so it has to be drilled into the heads of their victimspupils. In truth it's a kinda scruffy rule of thumb that basically stops people from claiming far too much precision in their results. It allows you to glance at a calculation someone gives you and be immediately suspicious of it if there are more digits in the result than in the input.
Furthermore, you need to know what the nature of those errors are. Suppose you're taking the average of ten numbers. If those numbers came from (say) a human measuring something with a tape-measure - then the errors are likely to be random - and normally distributed. Calculating the average of 10 numbers increases your precision because those errors average out. But if the error came about because the person was using a computer program that truncates input data instead of rounding it - then all of the error is in the positive direction and the average of those ten numbers is no more accurate than the input data. It's a very subtle business - and not one that I trust to these rules put out by well-meaning math and science teachers to schoolkids.
Of course, most kids fall asleep during this stuff because it seems so divorced from reality. A practical anecdote might help here: I'm in computer graphics for video games - and having a really good feel for the size of the errors and the sensitivity of the math to those errors ends up being critical. We deal with colors on the screen of your computer that are integers in the range 0 to 255 - about two and a half "sig figs". But the math that determines how light reflects off of shiney objects entails taking the direction of the incoming light, the surface direction and the direction of the eye/camera, then you calculate the cosine of the difference between the angle of incidence and the angle of reflection and raising it to the power of the shininess factor. OK - but the shininess factor is often a big number - 20 to 200 might be typical. Well, when you subtract two numbers that are similar in size - then raise the result to the power of 200 - the number of sig figs you need in your input data skyrockets! We typically need numbers that are accurate to one part in a billion to get good results - so the input data needed something like 8 or 9 sig figs. Urgh! On the other hand, if the object isn't shiney - so the coefficient of that calculation is more like 1 - then the input data only needs about 3 sig figs. We can take practical advantage of that by storing and handling the data to rougher precision for dull objects than for shiney ones. That means we need to send less data between the computer and the graphics card for dull objects - that means we can draw a lot more dull objects than shiney ones. THAT means that we can tell our artists that if they have their monsters NOT be slimey - they can have more monsters.
Proper error understanding means more monsters!...Math in action where it matters! :-)
Unfortunately, he can't just say no, he has no choice but to do his homework in the way he teacher wants it done. Sig figs are useless for doing any kind of calculations, where they are useful is in writing down uncertain numbers. It's much quicker to write "52.50" and have everyone know it means "52.50 +/- 0.005" than write "52.50 +/ 0.003", so you do it even though you're losing some precision. It's a good rule of thumb for knowing you precise your starting values are and for stating how precise your final figures are, but for everything in between, they're useless. They're often useless even for that, as an example I just came up with shows: Consider the sum 135+120, both figures are to 3sf. If we work out the correct answer we get 155 +/- 1, if we want to save space by not explicitly writing the error term we need to find a number of sig figs that doesn't mean we end up with false precision. 3sf clearly isn't going to do it, but it turns out neither does 2st since rounding to 2sf would give us 160 +/- 5 (don't get me started on how to round 5's!), which means the answer is somewhere between 155 and 165, but the answer might actually be 154, so we have to go all the way to 1sf and say it's 200 (1sf), which is correct but 50 times less precise than it could have been, so the number is probably completely useless. --Tango (talk) 01:55, 8 September 2008 (UTC)[reply]
I understand - and I agree. 100%. I just don't want students to graduate from high school imagining that the sig figs approach is any more than a rough rule of thumb. It's not taught that way - which is a major problem. When people start telling me that this is some kind of solid rule that "scientists" use - I get upset! In my job, having a solid feel for where precision get's lost - how to avoid losing it - where you need it and where you don't - is literally the difference between a great-looking video game and a terrible one. On the other hand, when someone on the WP:RD says that 220 million tons of coal is enough to last the UK for 400 years - and I do the math and wind up with just one year, it's nice to NOT say 0.845 years - and it's nice to know that it really couldn't really be 400 years because of roundoff errors - but it's a 'back of envelope' calculation and it's really not necessary to carry through anything more than a rough idea of the numbers of sig figs I'm using. So - as I said - the sig.figs approach is fine for 'back of envelope' calculations - but useless for serious work where the results actually matter. If an engineer designs a bridge that I have to drive over...I want accurate error tracking! SteveBaker (talk) 02:43, 8 September 2008 (UTC)[reply]
Ya gotta love WP:RD...in three hours I've gotten more helpful info on precision than in a year's worth of high school chem. Thanks a lot, everyone. This was very insightful! FlamingSilmaril (talk) 03:05, 8 September 2008 (UTC)[reply]
Thanks for your kind words - but PLEASE learn what your teachers teach - you need to get through exams, and if they require you to learn a pile of crap - go learn the pile of crap. Feel free to forget it later - but you need those grades! SteveBaker (talk) 17:29, 8 September 2008 (UTC)[reply]
Yeah, well said, Steve... I remember when I learned the real relationship between sig figs and careful error propagation, I thought, "I am way too old to be learning this for the first time." --Allen (talk) 07:26, 8 September 2008 (UTC)[reply]
Unfortunately, once you make it out of high school and into the realm of "professional science," there are all kinds of new silly specifications such as font-size and formatting minutia necessary for paper-publishing (which is in itself a dark and horrible cavern). It seems the same people who sit on school boards determining that SigFigs are relevant to high-schoolers are also sitting on paper-reviewing committees. I recommend obtaining and thoroughly learning a good word-processing suite which can handle formatting AND sig-figs so you can focus on the scientific task! As far as your data-processing, most of us do not have the constant need for real-time performance that Steve does, so we can perform over-kill and use more precision than necessary. But this is hardly a substitute for understanding the mathematical concept of error propagation. Even 32 or 64-bit calculations will only return what you asked them to return. Nimur (talk) 14:24, 8 September 2008 (UTC)[reply]
This stuff isn't only about writing research papers. Professional scientists do lots of actual practical work without ever writing a single paper in their entire lives. The discipline of maintaining correct precision throughout your calculations isn't just about getting your paper accepted - it's also about not having your bridge collapse - or (as in my case) making cooler graphics for your Xbox. That's an important thing - so many people do math and science in school, fondly imagining that they'll NEVER need to use any of this stuff in "real life" - when in fact, they really should. SteveBaker (talk) 17:27, 8 September 2008 (UTC)[reply]
If you are adding ten numbers, and each is +/- 0.1, why would you assume that the sum could be off by 1.0, which is the sum of the uncertainties? Wouldn't it make more sense to treat each one as a normally distributed uncertainty and take the square root of the sum of the squared errors? This would be the square root of 10 times 0.12 or .32? Edison (talk) 19:00, 8 September 2008 (UTC)[reply]
It depends on where your data comes from. For example, I once worked with some data-collection software with a strong bias for "+" in its data, so a total error of +1 was far more likely than a total error of -1 --Carnildo (talk) 23:25, 8 September 2008 (UTC)[reply]
Sometimes you do do things like that, it depends on the type of measurement. If the error is normally distributed, then you're right, but sometimes it isn't. One (rather bad) example would be where the error comes from the data having been previously rounded, then "+/- 0.5" doesn't means "there's a 68% chance it's between 0.5 less and 0.5 more" it means there's 100% chance, and the error isn't normally distributed, it's uniform. In that case, ten lots of +/- 0.1 does make +/- 1. (That's a bad example because you should never use data rounded off to a precision so low that it's a significant source of error, but there might be the odd occasion where you have no choice.) --Tango (talk) 09:56, 9 September 2008 (UTC)[reply]
Significant figures should be thought of as a way of introducing accuracy; it is not intended to be a rigorous mathematical tool. Perhaps sig figs are best thought of as another name for relative accuracy--that is, the error margin of a certain value compared to the value itself. To show how the relative accuracy is useful, consider a census. If a tiny community's population is reported to within 5 individuals, nobody would be impressed, but it would be shocking if the population of the entire U.S. is reported to within 5 individuals.
The example 0.125 g - 0.106 g = 0.019 can be thought of as: (1) There are two measurements that are reasonably accurate to within a certain absolute error margin. (2) When subtracting one number from another, the result should have double the absolute error margin. (3) Since the absolute error margin has been doubled and 0.019 is much smaller than 0.125 or 0.106, the error margin makes up a larger percentage of the value. (4) Intuitively, 0.019 should have less sig figs than the two original values.
I remember being taught sig figs in science class and calculating the actual error margins out of curiosity. The concept really is almost useless, and for that reason my teachers never required us to round answers appropriately on evaluations. It's useful to know that writing 2/3=0.6666666666666666666666666666666666666666666667 is not necessary, but that's likely as far as your chemistry teacher is going to go. --Bowlhover (talk) 05:00, 9 September 2008 (UTC)[reply]
This opens up another whole can of worms of course. If your data truly does have a normally distributed error pattern - then statistically, one sample can have an error that's a million times bigger than the "typical" value and even though you're averaging 10,000 samples together, that one outlier is enough to blow your error estimates off the chart. Worse still, if you multiply something with a normally distributed error by something else with a normally distributed error - you end up with a gaussian-squared error profile. Tracking the NATURE of the error through all of your math becomes a major mathematical nightmare. But at this point, you're more into the area of full-blown statistics than simple error tracking. However, even in relatively simple cases, this kind of thing becomes an issue. The round-off error in a floating point number in a computer depends on the magnitude of the number - the round-off error in an integer does not. SteveBaker (talk) 15:55, 9 September 2008 (UTC)[reply]
Dark skin and dominant/recessive traits
I know that darker eyes are a dominant trait contrasted with lighter eyes like blue eyes, which is a recessive trait. But what about darker skin? Is that a dominant trait as well contrasted with lighter skin? Is lighter skin a recessive trait compared with darker skin? ScienceApe (talk) 00:03, 8 September 2008 (UTC)[reply]
Unfortunately, it's not that simple, since there isn't just "dark skin" and "light skin", there is a whole range of colours. If someone with very dark skin and someone with very light skin has child, it will generally have skin somewhere inbetween. Talking about dominant and recessive traits only really works when the trait is governed by a single gene, which isn't the case with skin colour. --Tango (talk) 00:30, 8 September 2008 (UTC)[reply]
Robustness or lack thereof in "B-rex" (dinosaur question)
I know the validity of the robust/gracile morphotypes is uncertain, but does "B-rex" (MOR 1125)--the Tyrannosaurus specimen that was discovered to have medullary bone--fall into the robust or gracile morphotype? I know the robust morphotype is generally considered as more likely to be female, but am curious as to whether or not MOR 1125 supports this or not. 75.211.143.162 (talk) 01:47, 8 September 2008 (UTC)[reply]
Is this radiant energy exploitation possible?
1) Let there be a plane where the temperature is the same on both sides.
2) Let the plane have a hole in it. lets call one side the sending side and the other the receiving side.
3) Assume that there is a device on the sending side that will redirect and focus all ambient radiant energy that arrives in its collector and that its collector is the same size as the hole. Therefore the amount of radiant energy passing through the focus of the device would be the same as that passing in one direction through the hole in the plane.
4) Assume that this device is so arranged as to focus its output on the hole so that its focused energy is radiated through the hole in addition to what normally would pass through the hole.
5) In this case the receiving side should increase its energy (temperature) levels until its emissions through the hole matched those of the sending side. The energy (temperature) levels of the receiving side would be increased until its emissions matched those of the IMPLIED energy (temperature) levels of the sending side.
This is of course completely contrary to the 2nd law of thermodynamics as we would be moving energy from a colder to a hotter body and we would be decreasing entropy at the same time.
Some calculations -
Assume temperature of both sides starts at 300K (27 C) and a hole size 1 cm.
Therefore the amount of radiant energy passing normally through the hole is -
300^4 /10000 = 810,000 energy units (units of measure are not important because we work back to temperature)
We double the amount of energy passing through the hole by using the device.
810,000 * 2 = 1,620,000 energy units
The implied temperature of the energy passing through the hole is therefore
SQRT(SQRT(1,620,000*10000)) = 356.76K (83C)
Therefore the temperature of the receiving side will have to increase over time to 356K to balance the amount of energy passing through the hole.
Can you help and point out what I am missing? Or perhaps this actually works and for some reason that I cannot see, I don’t actually violate any laws of science.
You cannot have your assumption 3 device, which in itself violates the second law (the directed radiation has less entropy than the original undirected radiation). --Stephan Schulz (talk) 06:57, 8 September 2008 (UTC)[reply]
I agree with Stephan - step 3 is impossible - this "focussing" device breaks at least the second law of thermodynamics - since that's bogus, the whole concept fails. Maxwell's Demon is a more subtle problem - and the reasons why it fails are really rather subtle. SteveBaker (talk) 18:25, 8 September 2008 (UTC)[reply]
Probably not, no. Unless you hear about it everywhere - all newspapers, all TV channels etc - then it's most likely a hoax. The life on Earth will probably end in a few billion years, though, when the sun burns out and expands. -- Aeluwas (talk) 09:12, 8 September 2008 (UTC)[reply]
You're probably referring to the (fairly tiresome) controversy surrounding the Large Hadron Collider. No, it's not true; you can read more about the LHC and black holes here. In short, though: there's no reason to believe that there's any threat to Earth. Well, not from the LHC, anyway. (Also, you might want to think this through a little bit: if the world was known to end real soon now, don't you think there'd be some kind of serious discussion about it on a level that you couldn't help but notice instead of vague rumors and whatnot?) -- Captain Disdain (talk) 09:17, 8 September 2008 (UTC)[reply]
Certainly the world will eventually end. It's not likely to be a black hole that does it - but our own sun. As the sun starts to run out of fuel, it will gradually expand outwards, getting cooler and redder - swallowing up Mercury, then Venus and possibly also the Earth itself. But even if we don't get swallowed by the sun, the heat will boil away our oceans and probably blow away our atmosphere - eventually melting the rocks and everything mankind has ever worked for. Fortunately, the sun is barely halfway through it's fuel supply so this horrible event is many billions of years away. So mankind has plenty of time to think about building gigantic spacecraft and to start finding a younger star to live nearby. SteveBaker (talk) 17:20, 8 September 2008 (UTC)[reply]
There is an article on the end of the world which talks about even more ideas. Adding humans to the planet greatly increases the chances that something diffferent will end the world. Even if the LHC cannot destroy the earth, a hypothetical man made black hole that is big enough hypothetically could. Graeme Bartlett (talk) 21:21, 8 September 2008 (UTC)[reply]
Sure, there are all kinds of hypothetical ways we could destroy the world. A black hole is one of the more unlikely ones - nuclear war is several orders of magnitude more likely, for example. --Tango (talk) 09:59, 9 September 2008 (UTC)[reply]
It depends on what you mean by "end of the world". End of human civilisation? Probably in the next few million years. End of life on Earth? Likely to take millions, if not a few billion, years. End of the Earth as a discernable entity in space? Wait for the Sun to go nova, as described above. End of the universe? See what the article says. But destroyed by a microscopic black hole, or by an amazing planetary alignment, or just because we hit a date in some calendar that happens to coincide with the end of a cycle? Probably not in my lifetime. Confusing Manifestation(Say hi!) 23:09, 8 September 2008 (UTC)[reply]
No, it won't produce a nova - for that you need a binary star. But at the end of the Red Giant phase, there would be a "helium flash" - which would be just as exciting as a nova if you happened to be nearby! The hydrogen in stars the size of the sun gradually runs out - forming helium as it does so - and the core of the star collapses while the outer layers are expanding to form the red giant which is what will kill the earth. When the core has collapsed enough, (long after the Earth is toasted to a cinder) the sun will reach a temperature that is enough to start a helium fusion reaction (producing carbon). That's not a gradual thing - it happens for just a few seconds - and during that time the star pumps out a hundred billion times it's normal amount of energy! It's not a nova - but it's pretty damned impressive! This blows off the outer "red giant" stuff to form a "planetary nebula" while the core collapses into a white dwarf which eventually starts fusion reactions with carbon and onwards to higher and higher atomic weight byproducts. However, that exciting "helium flash" won't happen until the Earth is long-gone. SteveBaker (talk) 15:34, 9 September 2008 (UTC)[reply]
Don't do that! For safety reasons, it is very important to add sulfuric acid to water and not water to concentrated sulfuric acid. As I understand it, putting water into concentrated acid can cause the acid to spatter. Wanderer57 (talk) 13:06, 8 September 2008 (UTC)[reply]
The 'add acid to water - not water to acid' rule is important. The reason is that the resulting liquid can indeed splash, 'fizz' and splatter. If you screw up and add water to acid then the liquid that's splattering is concentrated acid...not good. If you do it the right way around and pour the acid into water - then the splattering is of water - or at least, very dilute acid. But even when you do it right - you have to be really careful. SteveBaker (talk) 17:12, 8 September 2008 (UTC)[reply]
Also the heat of solution seems less sudden. Acid-to-water, a small amount of acid dissolves, so a small amount of heat in a large container of water. Water-to-acid, lots more energy released by the solvation and for ultimately dilute solutions there is usually a very small solution volume with all that energy, so lots more heat. I've cracked several flasks by adding water to acid and by not using sufficient cooling. DMacks (talk) 17:35, 8 September 2008 (UTC)[reply]
Sulfuric acid is usually provided as a concentrated solution in water. (Usually 18 M, although your stock solution may be different - examine the container to be certain.) After determining the volume of dilute solution you need, calculate the number of moles of sulfuric acid you need for that volume (for 1 L, it's 0.13 mol; for 100 mL, 0.013 mol). Then determine the amount of concentrated solution you would need to give you that molar amount of sulfuric acid. (Once you get the hang of it, you can save time on the calculation by using the c1*v1 = c2*v2 trick.) Measure that out, and add it to almost-but-not-quite the amount of water you would need to bring the total volume to the desired volume, and once mixed bring the solution to the final volume with a small amount of water. (The convoluted procedure is needed because volumes aren't always additive.) This proceedure should have been explained in your beginning laboratory course - if you are unsure about your technique, I would recommend seeking skilled supervision before working with concentrated acids (... and then ask them to show you how to do it). -- 128.104.112.147 (talk) 15:48, 8 September 2008 (UTC)[reply]
TV detector vans
As many will be aware, everyone in the UK who watches television is legally obliged to own a TV licence. The money from these funds the BBC, since it is a non-commercial broadcaster. Anyway, enforcement of TV licence ownership is a big issue; see Television licensing in the United Kingdom#Licence fee enforcement. As that article states, TV detector vans are used in an attempt to trace homes that are watching TV without a licence. But there have long been suspicions that these vans are fake and just employed as a deterrent. This article states that the technology used by the vans is top secret. So, are TV detector vans really able to detect when a TV is on in a house? And what is this supposedly top secret technology? --Richardrjtalk email08:59, 8 September 2008 (UTC)[reply]
The "top secret" technology is most likely nonsense perpetuated from a simpler and more credible credulous age because:
I don't see how any "detector van" can possibly detect people who are watching non-broadcast television e.g. via cable or the internet (but, yes, they do still need a television licence).
This information leaflet from the BBC Licensing Authority says "TV Licensing’s policy is to visit all addresses where people inform us that no television is in use at the property" and "TV Licensing’s policy is to visit all addresses where people inform us that a black and white television is in use at the property" (and it makes no mention at all of detector vans !). So if the Licensing Authority makes follow-up visits at all properties which claim they do not need a licence or claim they only need the cheaper black and white licence, why invest in complex and expensive technology as well ? Gandalf61 (talk) 10:39, 8 September 2008 (UTC)[reply]
You can't generally do it sitting in a van, but it is fairly easy to send an electrical pulse down a cable line and estimate the number of splits and connected devices by measuring the reflections that come back. It only works if the number is small, so you need to be close to the end user, but it is a fairly standard technique for detecting illegal cable taps. Broadcast would be far harder, I'd imagine. (Unless the secret tech is "binoculars" and you are peeping in people's windows.) Dragons flight (talk) 10:46, 8 September 2008 (UTC)[reply]
Re. 1, investigation of the TV licensing authority website FAQ reveals that you don't need a license if you don't watch television as it's broadcast. Currently, this even means that you can watch the BBC iplayer without a license (as it only has programmes on-demand). [6]AlmostReadytoFly (talk) 10:55, 8 September 2008 (UTC)[reply]
I'm fairly sure it does streaming radio but if the BBC ever gets it into their head that they can charge me a licence fee just because I own a PC capable of internet access and could potentially go to their iPlayer website they can sod off. Its one thing when there are 3 out of 5 channels so you don't really have an excuse of "I don't watch the BBC channels" because you're likely to, but when its several billion webpages it gets silly TheGreatZorko (talk) 10:59, 8 September 2008 (UTC)[reply]
It does indeed do streaming radio, but the radio license has been abolished. I'm not sure how they would plan to cope with all the people telling them to sod off if they introduced live internet TV broadcast. I wouldn't be surprised if that's one of the reasons it hasn't happened. AlmostReadytoFly (talk) 11:13, 8 September 2008 (UTC)[reply]
Um cable? Why would they have to worry about cable? All they need is for the cable TV network to give them a list of subscribing households for them to check against their list of TV licensees. If someone has cable but not a TV license, well just pay them a visit... Same with paid satellite. I'm not sure if you need a license if you only use FTA satellite but even if you do, it's not that easy to hide a satellite dish so even if they can't detect you receiving satellite TV, they can probably detect your satellite. Nil Einne (talk) 11:37, 9 September 2008 (UTC)[reply]
Back to the question... It is possible to detect a flyback transformer in use. Until the current flat-panel televisions became popular, the flyback transformer was a very important part of all televisions. Detecting it is nearly identical to how (good) radar detectors, laser detectors, and anti-radar detectors work. They detect the emission of radio frequencies from the electronics. In the U.S., all electronics that I see have an FCC sticker on them that states that the radio emissions are within FCC guidelines - which basically states that it is emitting some sort of radio frequency. Usually, it isn't strong enough to be detected more than a few inches from the device. With the older televisions, I tested the range and was able to detect a television turning on and off from across the street. It was almost as powerful a signal as blenders and vacuum cleaners. Then, my whole "lets have fun with radio signals" ended when I was caught driving through neighborhoods and opening all the automatic garage door openers. -- kainaw™12:19, 8 September 2008 (UTC)[reply]
Could this principal be used to verify which channel is being watched? The claim was that the detection vans could tell which channel was being watched, since during the days of terrestrial television only two channels were BBC and hence liable for a licence. Jdrewitt (talk) 12:29, 8 September 2008 (UTC)[reply]
No - the law has always been that you have to have a licence regardless of what channels are being watched. If you never watch BBC, you still have to have a licence. --Richardrjtalk email12:41, 8 September 2008 (UTC)[reply]
The old analogue method of detecting the local oscillator in a turned on set could determine the channel being watched by the frequency detected. As the oscillator would emit a frequency that was always 39.5Mhz above the tuned in channel a simple bit of arithmetic would pinpoint what they were watching, eg - if a frequency of 793.75Mhz was received, subtracting 39.5Mhz would leave a detected value of 754.25Mhz which lies between the 751.25Mhz - 757.25Mhz band which is analogue channel 56 or BBC1 to you and me. I seem to recall something about the European Court of Human Rights either issuing a ruling or threatening action about this particular data capture as it was deemed outside of the requirements of enforcement to take note of someone's viewing habits. Nanonic (talk) 12:44, 8 September 2008 (UTC)[reply]
In this century of the fruit bat, when we now have plasma screens, satellite dishes, cable, digital TV, TiVo and TV tuner cards, I still don't see how it is feasible to remotely detect each and every instance of live TV viewing or recording. Far cheaper and easier to visit the relatively small number of properties that do not have a TV licence - which is what the Licensing Authority actually says it does. Gandalf61 (talk) 13:06, 8 September 2008 (UTC)[reply]
Actually, what they say is that they visit all properties whose owners claim not to have a TV (or to have a black and white one only). I can't find anything in that pdf that says what they do if you just ignore their rude and threatening letters; my own very limited experience is that they send more letters and do nothing. Algebraist13:14, 8 September 2008 (UTC)[reply]
My experience is that they send the threatening and rude letters regardless of whether or not you have a TV license, so I'm not sure there's any point in getting on at all. --Tango (talk) 13:22, 8 September 2008 (UTC)[reply]
I think the main way they catch people these days is by requiring an address whenever you buy a TV and then checking to see if you buy a TV license (or already have one) within a month of purchase, or whatever. It's not hard to get around that, of course. --Tango (talk) 13:22, 8 September 2008 (UTC)[reply]
all this chat about detection is a little bit hypothetical surely. I've happily watched tv without a license for years (shhhhh, it'll be our little secret). I've had a few threatening letters but ultimately Capita (who are the faceless corporation who run the enforcement side) aren't agents of the law and so cannot come into my house without a warrant. Surely, when you get the knock on the door, you just insist they get a warrant then sneak out and hide your TV at your neighbours house? Now that increasing numbers of us live in apartments blocks, you don't even have to put your socks and shoes on..82.22.4.63 (talk) 20:04, 8 September 2008 (UTC)[reply]
I believe that the TV licence enforcement people don't need a search warrant. Remember - the UK doesn't have a constitutional right for individuals to not be searched as there is in the USA - in fact, we don't have a constitution. So I believe, the guy will simply enter your home anyway. Plus, if they do detect you are using a TV, that evidence can probably be recorded and used in court without them actually finding the TV set. My father always swore he was going to buy two VCR's - use one of them to record TV shows and the other to play them back into a TV that he'd remove the UHV demodulator from. The result would be that he would not own a device capable of viewing broadcast TV - and would therefore be off the hook legally speaking. Of course, like the rest of us with clever schemes, he just paid up for the license fee.
Of course they need a search warrant. You don't need to have a written constitution to have laws against breaking and entering and trespass. --Tango (talk) 23:50, 8 September 2008 (UTC)[reply]
Frankly, in the more confusing maze of modern TV watching technology, and with virtually 100% of the population watching TV anyway - the government should just turn it into a regular tax. This idea has been fought for a long time because the original idea was to have the BBC funded by the TV license fee in order to give them independance from government control - so they could be truly neutral in reporting government matters...but I think that could be achieved in other ways - such as requiring the government to fully justify any reduction in BBC funding relative to current inflation...but the idea of 100% independence is a good one.
"The annual cost of a colour TV licence (set by the Government) is currently £139.50. That works out at less than £12 per month - about 38p per day for each household. A black and white TV licence is £47. The licence (whether colour or black and white) is free if you are 75 or over, and half-price if you are registered blind, although you still need to apply."
So the full thing is roughly $260 US per year. (And it's TOTALLY worth it - I'd rather pay that much for a couple of BBC channels without adverts than the roughly 2x that amount I pay for 200 channels of advert-laden crap.) And it's half price if you're blind? Wow - so the audio part of the signal is half the cost but the color part of the video signal is more than two thirds of the cost? Whatever happened to "A picture is worth a thousand words"?! There must be a huge market in black and white TV's for blind people! :-) SteveBaker (talk) 21:45, 8 September 2008 (UTC)[reply]
How does antigravity point work? In Salalah (Oman) there is a place where cars roll uphill from this point. Any scientific explanations?
ref:-
http://www.salalahport.com/salalah.asp
"...the anti-gravity thingy kicks in your vehicle instead of rolling down the
slope begins to roll back UP hill."
(Sadly, your spirit level test is meaningless - if there really was antigravity - then it would make your spirit level work incorrectly too. The same thing is true for plumb-lines. All of those devices measure the direction of prevailing gravity - so if there WAS antigravity, they'd produce the same result as cars rolling, etc). SteveBaker (talk) 17:04, 8 September 2008 (UTC)[reply]
I suppose the spirit level would be valid if it were a magnetic (rather than anti-gravity) hill, but thanks for pointing this out, Steve -- I've noticed the problem myself before and wondered if I was just thinking too hard. — Lomn00:17, 9 September 2008 (UTC)[reply]
A compass would handily rule out the possibility of a "magnetic hill". If it points "up" the hill - then yeah - it's a weird (VERY WEIRD) magnetic effect. If it carries on pointing North...then it's busted. Of course if the hill runs "up" to the North, that's not gonna prove anything...but with a reasonably sensitive compass, you can still figure it out. But the truth is that a freak magnetic effect would either:
Be VASTLY stronger at one end of the hill than the other (magnetism is an inverse-square kinda thing)...to the point where if it could start a car rolling uphill at a distance of (say) 1 km from the magnetic source - then the force would be 1,000,000 times stronger at the "top" of the hill where the magnet would have to be - and nobody would be able to move the car once it got there.
...OR...
Be more or less even in force all the way along the hill - in which case the magnet would have to be situated hundreds of miles away and be a field would have to be VASTLY stronger than the Earth's. If that kind of gigantic magnet existed, it would be detectable everywhere on the planet.
This is more fun by far than the original question. I propose we use two spirit levels connected by a long pole. We calibrate them to agree with each other in an area of known-good gravity and then take measurements every few feet in the area of the magic hill. If the two levels suddenly disagree we'll know there is a problem with the local gravity. APL (talk) 20:45, 9 September 2008 (UTC)[reply]
Well, if you intend to throw down the "weird side-effects" gauntlet: Antigravity would be easily detectable because the density of the air above the region of reversed (or reduced) gravity would be reduced. This 'lighter' air would rise like warm air does - but the winds blowing towards the antigravity source would instantly reduce in density - rising to be displaced with more heavier air...pretty soon you'd have a really impressive toroidal tornado thing. SteveBaker (talk) 03:15, 10 September 2008 (UTC)[reply]
There is certainly no such thing as anti-gravity. There are plenty of these "magic hills" around - and what's really going on is that the hill slopes in the direction you'd expect for things to be rolling downhill - but something about the surrounding topography fools your eyes into thinking that the hill slopes in the opposite direction. Sometimes it's because the surrounding terrain gives you a false idea of where the horizon is - sometimes it's because of a strong prevailing wind running up a valley that makes trees grow with a slight slant...whatever it is, it's never "antigravity". SteveBaker (talk) 17:02, 8 September 2008 (UTC)[reply]
I am a student of Physics and I can confirm that the slope does exist and it is not an optical illusion.
There is side wall which clearly goes up and the masons would have used the water level or the plumb line to do the construction, and both would apopear to follow the ground level, instead of the horizon. Fortunately, the sea and the horison is visible from the point in Salalah, the upgradient is remarkable and clearly visible. But the theory of ANTI GRAVITY is foolish, since there no such thing, but a gravity gradient is possible. The higher weight of an iron mountain on one side and a loose lime stones on the other side may produce such an effect. Since the road is above a big wide gap in the mountains, this is possible with a deep underground fissure which separates the two mountains. (Ajith, after visitng the site on 9-8-2013)
Encyclopedic?
This is a section from the article about the herbicide Roundup.
"==Genetically modified crops==
In 1996, genetically modified Roundup Readysoybeans resistant to Roundup became commercially available, followed by Roundup Readycorn in 1998.[1] Current Roundup Ready crops include soy, maize (corn), sorghum, canola, alfalfa, and cotton, with wheat still under development. These cultivars greatly improved conventional farmers' ability to control weeds since glyphosate could be sprayed on fields without hurting the crop. As of 2005, 87% of U.S. soybean fields were planted to glyphosate resistant varieties.[2][3]
The use of roundup ready crops has changed the herbicide use profile away from atrazine, metribuzin and alachlor. This has the benefit of reducing the dangers of herbicide run off into drinking water.[4] The use of roundup-ready crops has resulted in greater use of roundup, which has created a problem with weeds that are resistant to the herbicide. With greater use, it has become more likely that weeds that are not effected by the herbicide, survive and reproduce and proliferate.[5]"
Would it be fair to say this reads more like an advertisement than an encyclopedia article?
If that were the entire article I'd think it was a little unbalanced but the rest of the article contains extensive sections devoted to the many criticisms of Roundup. A section listing the products and the benefits to the farmer is not out of place, even if it is only part of the story. I suspect "conventional" here is to distinguish from "organic" but I don't know. --98.217.8.46 (talk) 13:47, 8 September 2008 (UTC)[reply]
The reference desk is not an editing board for the rest of the wikipedia project; we're just here to help answer factual questions that people can't find answers to themselves. Issues concerning the content of an article are best dealt with on the discussion page of the article in question. --Shaggorama (talk) 08:27, 9 September 2008 (UTC)[reply]
And yes, "conventional" is often used in grocery stores that also stock organic produce (e.g., the Whole Foods chain). "Organic" means free from pesticides, bovine growth hormone, what have you; "convention" means "no such guarantee." So in this sense a conventional farmer is one who doesn't warrant that his crops are organic. --- OtherDave (talk) 21:40, 9 September 2008 (UTC)[reply]
Wellbrutrin and Libido
I have read somewhere that the drug Wellbutrin has caused some increased libido in women. Do you know why this happens? Is they a similar drug that has the same effect? Can anyone find this article? --Anilmanohar (talk) 13:52, 8 September 2008 (UTC)[reply]
I just noticed a parasite under the fur of my kitten and I'm trying to identify it (New York). My first thought were fleas, however: (1) they seemed to long and thin to be a flea, they were approximately 3-4mm long, and (2) they scurried/ran rather quickly, which I didn't think was the way fleas moved. (Does this fall under the auspices of medical advice? I will be making a call to the vet later today, nonetheless) -- MacAddct 1984(talk • contribs)14:53, 8 September 2008 (UTC)[reply]
We can't give veterinary advice either - so for "what should I do to help my cat?" you certainly should do what you have said, and go to your vet. If you post a photo of the critters and ask "what are these? They live on a domestic cat in [insert country name here]", then I am sure we will do our best to help identify them. DuncanHill (talk) 15:24, 8 September 2008 (UTC)[reply]
Sounds like fleas to me. They can look like you describe and they can scurry like the devil. They're horrific little things. When my cat had them they were like little hard dark grains of rice. Gross to the max, as they say. Fortunately there's stuff you can put on them that takes care of them pretty well. We used Advantage or Frontline or one of those things. But check with the vet, esp. if it is a kitten. --98.217.8.46 (talk) 16:22, 8 September 2008 (UTC)[reply]
Fleas will certainly scurry when they're in among fur. It's only on hard surfaces that they resort to hopping. A flea comb is very satisfying to use if you don't want to use the medications .46 suggested. --Sean17:07, 8 September 2008 (UTC)[reply]
Cats and Dogs WILL pick up these kinds of thing - they need protection - and something like Advantage is a good choice. However, with very young animals, you have to be super-careful. Lots of those chemical treatments can't be used on them until they get older. Kittens have to be more than 8 weeks old before you can use either Frontline or Advantage (for example). If your cat is a younger than that - then talk to a vet, tiny kittens can become aneamic from repeated flea bites. If older than 8 weeks - nuke the little brute with chemicals and keep doing it every month for the rest of it's life! You may also want to attack your carpet with something like this. SteveBaker (talk) 18:18, 8 September 2008 (UTC)[reply]
The newly-discovered Vernulles effect
The article Airsoft talks about the "Vernulles" effect. This article is the only use of the term "vernulles" found by a Google search, so it is either wrong or a new effect known only to Airsoft.
I suspect it is meant to be Venturi or Bernoulli. Perhaps someone else will take a look at the description of the Vernulles effect.
They are upgrading the wide-angle camera (no use for looking at teeny-tiny planets) and adding a new spectrograph (no pretty pictures there!).
The main thing they are there to do is to replace the gyroscopes, add new batteries and replace the heat blanket. They are also adding a docking ring so they can send up an unmanned craft to safely de-orbit the telescope when it finally does die. The mission is especially important because the gyros on the telescope are dying one by one and when the last one dies, the telescope will start tumbling - which will have three bad effects: Firstly, it won't be any use as a telescope, Secondly, a shuttle mission would be unable to fix it because the shuttles robot arm wouldn't be able to grab it without getting ripped to shreds, and Thirdly because de-orbiting the telescope safely would be impossible and it's a REALLY big spacecraft to come smacking into the middle of a city. Replacing the batteries is important for the same reasons - they power the gyros when the craft is in the earth's shadow and the solar panels don't work. The Hubble has always had problems with overheating - so the new blanket will help it stay cool.
The only other thing they are doing that MIGHT improve that picture is an upgrade to the Hubble's pointing mechanism. If you can point the telescope accurately then in principle you can get more precision when photographing planets by taking a bunch of photos at different times and with the camera aimed a fraction of the size of a pixel to one side or the other - then averaging the photos all together at higher resolution. But I doubt the new pointing mechanism is going to help that enough to make a better image.
As the earth rotated while time passed, is there the possibility that folks at some other location saw a different phase of the moon? Does this ever occur, that there is a "phase transition" during one 24 hour day? Edison (talk) 05:00, 9 September 2008 (UTC)[reply]
Well sure, if you're seeing it at different times. Technically - you'll see a SLIGHTLY different phase when you are in a part of the world where the moon has just risen than at the exact same moment in time when your on the opposite side of the world and the moon is setting. That's because you're seeing the moon from a slightly different angle. So strictly speaking, one person could see it (say) fractionally before "full" and someplace else could see it fractionally past "full"...but it's a very tiny effect. SteveBaker (talk) 06:35, 9 September 2008 (UTC)[reply]
Yoursky can plot the sky for any location and probably any date you'd ever be interested in. Here is what the sky looked like above San Francisco, CA on August 15, 1972 at 02:00 UTC (19:00 Pacific Daylight Time on August 14). --Bowlhover (talk) 03:56, 11 September 2008 (UTC)[reply]
Speed of engulfment by LHC black hole
I know, I know, the LHC isn't going to create a black hole that will swallow us all up. But if it did... If a tiny black hole were created that was stable enough to continue existing, and strong enough to suck in the LHC, Switzerland and the rest planet, how long would that all take? Would the boundary expand at the speed of light, or would we have a few hours to get drunk and make a few phone calls?
— Sam 19:38, 8 September 2008 (UTC)
Even ignoring Hawking radiation, you would comfortably die of old age. Gravity is a very weak force, and black holes are only potent because they have huge masses. A micro blackhole is much smaller than atoms and thus has trouble eating anything. It could well take longer than the age of the universe to grow a TeV black hole to a size you would notice. Dragons flight (talk) 19:50, 8 September 2008 (UTC)[reply]
A tiny black hole would weigh very little - so it would have VERY little gravity. The only reason it could grow at all is because it's not only very lightweight but also very, VERY tiny. Since gravity gets much stronger the closer you get to something (and you can get very close indeed to a micro-black hole because it's so small), eventually it's gravity is as strong as a star-sized black hole - more than enough to suck things in. But by "close" I mean "much less than the size of an atom" (MUCH less). So these things would be attracted to the center of the earth - but they are so small and need to get so close to something that it might take them years before they'd actually happen to get close enough to suck in even one atom. At that rate of growth, the sun would have died and swallowed the earth long before the gravitation of the micro-black hole could get big enough to eat the planet. Hence, they really aren't of much concern. But if we believe in Hawking radiation (and that Hawking fellow is no slouch when it comes to the physics of black holes!) - then these micro black holes will "evaporate" in such an amazingly short amount of time that they essentially don't exist at all. So don't sweat it - you'll have plenty of time for your great-great-great-(...)-grandchildren to get virtual-drunk, send a few telepathic emails and ask the same question over on the Hyper-pandimensional-wiki-mega-pedia Ref Desk. SteveBaker (talk) 20:59, 8 September 2008 (UTC)[reply]
That's simply not true: a black hole exerts the exact same gravity as would any object of the same mass, no matter how close you come to it. Gravity does *not* become asymptotically strong is you come close to the event horizon. --baszoetekouw (talk) 06:50, 9 September 2008 (UTC)[reply]
Oh - but it most certainly is true. Ask yourself this: How come it's a black hole? To be black, the gravity field at it's teeny-tiny event horizon has to be so strong that light cannot escape from it...that's some seriously strong gravity - even though the darned thing weighs about as much a couple of atoms. Besides, the math is very clear: Per Sir Isaac Newton (the guy with the apple)... F = G x ( m1 x m2 ) / r2 when 'r' (the distance between two objects) gets small enough - 'F' (the force between them) can reach any arbitarily high value you'd care to choose. Since a black hole is a singularity (it has literally zero size), you can get to within zero distance of it - and F becomes infinite! With normal atoms, you can't get close enough to them without the strong nuclear force stopping you...but when one of the objects has collapsed into a singularity, you can get as close to it as you like...and sooner or later, it's gravity is as strong as any galaxy-eating monster. Of course, a billionth of a meter further away from it and the gravity is so close to zero you can't even tell it's there. But that's the entire point! SteveBaker (talk) 23:58, 9 September 2008 (UTC)[reply]
It doesn't become arbitrarily strong as you approach the event horizon, it becomes arbitrarily strong as you approach the singularity. However, the event horizon of such a small black hole would be very close to the singularity (closer than you can get to an atom) so, even though the mass is tiny, the gravity would still be very large (an escape velocity equal to the speed of light, by definition - give or take some GR effects). --Tango (talk) 00:03, 10 September 2008 (UTC)[reply]
That's true - it doesn't become arbitrarily strong at the event horizon - but it does become as strong as any star-eating black hole. The gravity at the event horizon of absolutely any black hole is (by definition) such that the escape velocity is equal to the speed of light. That has to be true of absolutely any black hole...no debate. And if you do cross the event horizon, the gravity will steeply rise to infinity at the singularity. But when you are at a distance comparable to the radius of an atom, the gravity has dropped to completely negligable amounts. It's asymptotic alright!
Guys, it doesn't become "arbitrarily strong" anywhere, it tends towards infinite strength the closer you get (in current theory anyway, God knows with Quantum Gravity). It would be some pretty bad physicists that were announcing that the results of their experiments were "arbitrary"! Deamon138 (talk) 03:04, 10 September 2008 (UTC)[reply]
Yowza. Okay, there are at least two different notions of "gravitational field" that could be relevant here. The coordinate-independent (i.e. generally covariant, i.e. measurable without outside reference) gravitational field goes to infinity at the singularity. It does not go to infinity at the event horizon. But the coordinate-independent field is the tidal force, which is not what people normally mean by "gravitational field". The acceleration of gravity—i.e. the amount you have to accelerate upward to stay at the same distance from the hole—goes to infinity at the event horizon. Also, the strength of the generally covariant field (tidal forces) at the event horizon is larger for less massive black holes, but the strength of the generally covariant field or the acceleration at a given distance from the center is roughly proportional to the mass. And "becomes arbitrarily strong" is just another way of saying "tends to infinity", at least to physicists. -- BenRG (talk) 11:49, 10 September 2008 (UTC)[reply]
To put it really simply - such a small black hole would have next to no gravity so things would only "fall" into it if they happened to crash directly into it by random chance. Remember, this black hole is smaller than an atom and atoms are mostly empty space, so it's very unlikely for anything to crash into it, it will just go through all the atoms. --Tango (talk) 21:24, 8 September 2008 (UTC)[reply]
I looked this up for a similar question a few weeks ago. I don't remember the exact figure, but suffice it to say that it is many many times longer than the expected lifetime of our sun. Not only will we be dead an gone long before that becomes an issue, but so will our entire solar system. PlasticupT/C01:21, 9 September 2008 (UTC)[reply]
Ridicule me if you will, but I have a couple of decent questions. First off, we know that the experiments at the LHC have been performed in nature numerous times. Is there a difference between the collision of cosmic rays and stationary matter as opposed to matter moving about as fast in opposite directions? Second thing: if such collisions occur in the entire universe ten millions times per second, what would happen if they occur sixty times more often in a very, very close space? Proven or theoretical answers would be appreciated. —Preceding unsigned comment added by 66.183.135.96 (talk) 01:01, 10 September 2008 (UTC) —Preceding unsigned comment added by Hey Lao (talk • contribs)[reply]
Well, I can't really answer specifically your questions, but as far as I'm aware, there isn't much difference between collisions in the atmosphere and that will take place at the LHC. The only real difference (and effectively the reason for the project) is that the LHC collisions are controlled by the physicists, and there are cameras and computers and god-knows what else, recording the results. Obviously this can't be done with the cosmic rays, so it's controlled nature is what sets it apart. Deamon138 (talk) 03:12, 10 September 2008 (UTC)[reply]
Actually, this is one of the more rational objections to the LHC. With cosmic ray collisions, it's overwhelmingly likely that an incoming particle moving at close to lightspeed will smack into something more or less stationary (a rock perhaps). Conservation of momentum means that the resulting mini-black-hole/strangelet/whatever will shoot off at a substantial fraction of the speed of light. But in the LHC, the two particles are approaching each other with equal and opposite speeds - precisely so that their momentum cancels out and the collision products will be more or less stationary, so they can be observed. So a 'problem' particle caused by a cosmic ray would be halfway to the moon before you could blink - but if a strangelet were to form inside the LHC, it would truly be the end of the world within not many seconds.
Mini-black holes are really no concern whatever...it's strangelets that are deeply scarey.
I was wondering if anyone can tell me if carbolic acid is effective in killing roaches. A neighbor told me it was but I cannot find the stuff in any stores. Any assistance would be greatly appreciated. Thanks! —Preceding unsigned comment added by Leathergurl (talk • contribs) 20:30, 8 September 2008 (UTC)[reply]
One reason you might not be able to find it is that it is rather toxic. Around the turn of the 20th century it was a very popular means of suicide (many stories from that time refer to people taking their lives with 10¢ of carbolic acid). The stuff you ought to be looking for is boric acid, said to be very effective against roaches, and much less toxic to humans [7]. - Nunh-huh20:57, 8 September 2008 (UTC)[reply]
Hi, I don't know which desk this goes under but does anyone know any companies (preferably well known ones) that in whole or in part are involved in control systems engineering? I've been looking for some but I can only find relatively small, unheard-of companies. Thanks. 202.37.62.221 (talk) 23:38, 8 September 2008 (UTC)[reply]
Lots of big companies use or support research in control systems engineering, you may for instance google "model predictive control" and StatoilHydro or the name of other big oil companies. But if you'r looking for a company that has control system engineering as their core business, many of these are companies in niche markets and thus smaller and less well known. But anyway, a quick glance at a list [8] of SCADA and automation companies quickly reveal ABB Group and Honeywell which I guess are fairly well known names. EverGreg (talk) 10:31, 9 September 2008 (UTC)[reply]
HIV taxonomy
To which kingdom does it belong? I have been able to find the genus and family but not the kingdom. Not even on Virus Taxonomy Online or the ICTVdb Index of Viruses
A lot of biologists would dispute that viruses are even life-forms. It's a thin line between complicated chemical agents and actual life. SteveBaker (talk) 04:45, 9 September 2008 (UTC)[reply]
Does anyone who's anyone still believe that prions are alive? I know that there was a bit of debate about that a few years ago, when Mad Cow was in the news. --Kurt Shaped Box (talk) 06:16, 9 September 2008 (UTC)[reply]
From that article and others, we can see that there is no scientific consensus on a taxonomy with a single root, so there is no virus "kingdom." For the other kingdoms, it is reasonable to assume that each kingdom arose from a common ancestor and that the kingdom divided by evolution and natrual selection into finer and finer divisions, each with a common ancestor (approximately.) This is not likely for viruses. Viruses are likely to have arisen multiple times in multiple hosts. Therefore unless a bunch of viruses appear to be similar enough to suggest evolution from a common ancestor, scientists are unwilling to assign them to the same grouping. -Arch dude (talk) 14:07, 9 September 2008 (UTC)[reply]
September 9
Check this out?
I know it seems ridiculous, but could someone with some scientific background look into this? It appears to be unlikely, but I'm just wondering, does it have any scientific truth?
What is there to say about it? He never really says how he did it, or what evidence there is it works. He's just asking you to blindly hand over 25M...Someguy1221 (talk) 01:19, 9 September 2008 (UTC)[reply]
Now there's a potential scam, ripe for the exploiting. Tell the mark that you're collecting payment in cash, as arranged, for time-travel related services rendered in the future and that all will be made clear if they go check the eBay auction/website on <date in future> and make contact... --Kurt Shaped Box (talk) 06:14, 9 September 2008 (UTC)[reply]
Oooh! That's good! You wear a shiney silver costume and knock on people's doors: "Hello! I'm a time traveller from 20 years into your future. The future-you told me to come back in time and tell you to invest $10,000 in this company so that when the stock price skyrockets next week you/he will become a multi-billionaire." ...very good! SteveBaker (talk) 15:12, 9 September 2008 (UTC)[reply]
Wow! That's a pretty bold con trick! I like the way that there is ZERO information on any of the pages. I've filed a fraudulant sales report with eBay.
He's given himself "3 to 5 years" to spend the cash and find someplace to hide from his investors. If it really worked, his future self would already have gone back in time and told himself which horses to bet on to get the cash to develop it...and probably given himself the plans and the dilithium crystals to make the work take less time. I guess that's how we know it's not real.
Ahh, A a little GF wouldya? The guy might just be your common-or-garden internet nutcase - or just another attention/lulz-seeking hoaxer. ;) Seriously though, if that auction stays open, it will attract bids from people with no intention of paying (that's not intended as an incitement to do that, seriously, guys!) - these things always do. I don't know offhand what the Final Value Fee on $25million will be - but it won't be small... --Kurt Shaped Box (talk) 06:10, 9 September 2008 (UTC)[reply]
WP:AGF is a Wikipedia rule - it doesn't apply in real life. When someone is so clearly attempting to scam some gullible investor out of millions of dollars - I regard it as my responsibility as a rational human being to do something about it. In this case he's clearly breaking eBay's bylaws - so I reported him. If he breaks Wikipedia guidelines, I'll report him for that too. There aren't many rules on the Internet - but where there are, let's try to enforce them. SteveBaker (talk) 06:29, 9 September 2008 (UTC)[reply]
Oh come on, be fair!! He clearly does say how it works - dimensional tunneling, whatever that is. I am a little puzzled why he does not just send a completed machine back in time though. It would avoid all those tedious development costs. SpinningSpark15:54, 9 September 2008 (UTC)[reply]
My daughter is doing a school report and needs to find out Reno's proximetry to the ocean.
(removed e-mail address to protect from spambots)
75.15.211.224 (talk) 03:28, 9 September 2008 (UTC)Brandi[reply]
We aren't supposed to do people's homework - but I would suggest going to Google Maps - enter "Reno, Nevada" then back out until you see some ocean. Pick a city on the coast and ask Google to plan a route from Reno to that city. That would be the driving distance - the "as the crow flies" distance will be a bit shorter. SteveBaker (talk) 04:33, 9 September 2008 (UTC)[reply]
And to find the crow's distance easy, if you have Google Earth, you can click on the ruler button to drag a line between two points, and the program will tell you the distance you've just drawn across. Someguy1221 (talk) 05:02, 9 September 2008 (UTC)[reply]
(When you look at the map - it's pretty clear what the nearest city is (hint: it has a really pretty orange bridge) - and that driving route is pretty direct...in this case). SteveBaker (talk) 05:28, 9 September 2008 (UTC)[reply]
I think it's generally caused by being distracted while speaking, you're thinking one thing and saying another and you end up saying something else (often related to what you were thinking). You may like to read Freudian slip. --Tango (talk) 10:59, 9 September 2008 (UTC)[reply]
Check my chemistry questions
I have the following questions and the answers Ive gotten are below each one. Tell me if they are correct:
Write the full equation for sodium reacting with bromine to form sodium bromide
Na2 + Br2 -> 2NaBr
Write the half equations for the same reaction
Na2 -> 2Na+ + 2e- and Br2 + 2e- -> 2Br-
State which species is being oxidised and which is being reduced
Br2 is oxidised. Na2 is reduced.
State which is the oxidant and which is the reductant
Na2 is the oxidant. Br2 is the reductant
I think its pretty much right but one thing Im definitely not sure of is this: in questions 3 and 4 should my answers read, for example, as I said "Br2 is oxidised" or "2Br- is oxidised"
Thanks --RMFan1 (talk) 12:26, 9 September 2008 (UTC)[reply]
You're on the right track as far as balance. Check the redox page for definitions of the various terms and roles of the reductant and oxidant. Regarding notation, something written as Xy means a single molecule (or polyatomic ion) consisting of y atoms of element X together. Writing yX means a collection of y distinct X atoms or polyatomic ions. So you have to figure out whether there is such thing as, for example, an actual molecule composed of two bromine atoms or whether bromine exists as single atoms (and therefore you'd just have two of them). You can read our bromine and sodium pages to see what their stable forms are. DMacks (talk) 14:32, 9 September 2008 (UTC)[reply]
Redox has the defs:) I usually try to think about it in terms of the charge on each atom and whether it's going down (being "reduced") or whether at atom is doing something to cause another atom's charge to go down ("reducing" it). DMacks (talk) 01:25, 10 September 2008 (UTC)[reply]
There are two major mistakes in your homework. However the Wikipedia reference desk is not supposed to be for your homework questions. Axl ¤ [Talk]20:12, 11 September 2008 (UTC)[reply]
If memory serves, the alien in Alien wasn't capable of space travel, it only became a threat because the humans on the film went to its planet. I very much doubt an alien like that can exist anywhere in this solar system (except possibly Earth, but then it wouldn't be an alien!), so until we invent interstellar travel we should be fine. After that, it's anybody's guess! --Tango (talk) 13:22, 9 September 2008 (UTC)[reply]
It's a kind of CO2 sequestration technique - except that it's really not going to work long term.
The idea is to capture the CO2 produced by some kind of nasty coal fired power station - use sunlight to cause algea to convert that CO2 into carbohydrates - then to harvest the algea and convert the carbohydrates into methanol or something - which . However, when you use the resulting fuels - the CO2 is released into the atmosphere again...so you didn't sequester it. Someone will probably argue that when you burn these new fuels, you could use the same technique to sequester that CO2 - but now you have an infinite regress because you're continuing to pump CO2 into the "system" so more and more and more algea are needed in order to sequester it. The only answer is to NOT convert the algea into any kind of a fuel at all - but instead to dump it back underground. The trouble is that the cost of doing all of this is so high that you can't afford to just dump the results back into a hole in the ground.
If you are going to invest in a "solar to ethanol" plant - then do it without the nasty power plant generating the CO2 - let the algae take the CO2 from the air - that would be a truly "carbon neutral" solution.
So - this is another effort by the "Clean Coal" people to pursuade us that they can continue to build big, polluting coal-fired power stations without killing the planet. They just hope that by confusing the science like this that the general public will fall for it...and the annoying part is that they probably will because the problem with it is pretty subtle.
It sounds like the idea is to take advantage of the concentrations of CO2 that you get at the source in order to grow the algae more efficiently, it's not a CO2 sequestration technique (if it's being described as one somewhere, I expect that's the press not knowing what they're talking about). --Tango (talk) 15:11, 9 September 2008 (UTC)[reply]
Yes, you are right. Although the algae could be used to permanently sequester carbon by turning it into biochar, bio-oil and syngas the idea here is much more sophisticated. Some algae species produce up to 50% of their body weight in vegetable oil, which can be extracted first and even tailored to produce compounds that lend themselves better to one form of end product than another such as jet fuel versus heating oil versus salad oil. The remaining components can then be used as a dietary supplement or as cattle feed or as feed stock for biochar, etc. —Preceding unsigned comment added by 71.100.10.144 (talk) 16:28, 9 September 2008 (UTC)[reply]
Well you're not adding to the problem you're just recycling stuff that's already been released from fossil fuels. It's not a solution but you seem to insinuate that you're making it worse when you're not you're just keeping the problem the same and making some energy at the same time right? Dereconstruct (talk) 22:15, 12 September 2008 (UTC)[reply]
You generally need a specific product name, then you can use Google to search for "xxx hazard symbols". For instance, I was able to find the safety data sheet for one Liqui Moly product: [9] and the symbols are Xn, R42, S2, S23.3, S45 and S51. You can reference the meaning of the symbols here: [10]. Franamax (talk) 00:28, 10 September 2008 (UTC)[reply]
crossbreed dogs
I'm pretty darn sure it's possible to breed two different species of dogs together, to create a mixed-breed dog. Can all species of dogs mate with all other species of dogs? Or are there cases where it doesn't work? Bradley10 (talk) 15:56, 9 September 2008 (UTC)[reply]
Duncanhill, is that sort of thing possible, if inadvisable? Is it because of the potential size of offspring, or the physical difficulties of such a coupling? Not to mention the tie? Bradley10 (talk) 16:14, 9 September 2008 (UTC)[reply]
I am not a dog breeder, but I suspect that all the things you mention would conspire to make it physically impossible, though of course, as members of the same species they would theoretically be capable of producing viable offspring. DuncanHill (talk) 17:12, 9 September 2008 (UTC)[reply]
It is possible to crossbreed all dogs (assuming the male and female you use can breed). In a professional sense, any obstacles with dog size and temperament do not matter. The sperm is collected from the male and the female is artificially inseminated. Of note, wolves can be crossbred with dogs as well, but you do not get tame wolves. You get dogs that will snap and attack anyone and anything at any time. -- kainaw™18:00, 9 September 2008 (UTC)[reply]
And, of course, we have an article: Wolf-dog hybrid with a section that goes to great lengths to claim that while wolf-dogs have an erratic temperament, it is not possible to know exactly how any dog will act in all situations. Way to rationalize there! -- kainaw™18:03, 9 September 2008 (UTC)[reply]
Medicval term for 'facial flushing'
Niacin says "People taking pharmacological doses of niacin (1.5 - 6 g per day) often experience a side-effects that can include dermatological complaints such as facial flushing and itching, dry skin, skin rashes..." (my bold). What is the medical term for facial flushing? RJFJR (talk) 16:15, 9 September 2008 (UTC)[reply]
Nah, we're right smack in between Cycle 23 and 24, so things are at a minimum right now. They should begin to pick up again soon, (hopefully for my DX'ing), but its not unheard of for a minumum to stretch out for a bit (see Maunder Minimum) ArakunemTalk17:05, 9 September 2008 (UTC)[reply]
Yes, high solar activity improves skywave propagation because the increased radiation helps ionize the ionosphere that long-wavelength radio waves reflect off of (see http://www.blackcatsystems.com/propagation/solar_flux.html). On the other hand, solar flares are more frequent during the solar maximum and can cause propagation to vary wildly.
It has a huge effect, with high sunspot parts of the cycle propagation of much higher frequencies occurs even into the low VHF bands. The signals bounce off the inside of the ionosphere back to the earth, and then up and down of the earth again. Though if you want to receive low frequencies from Space say 1 MHz, or get a clear GPS signal, then now it the opportunity. Now all the shortwave stations have to pack themselves down the low frequency end where there is more interference and absorption, and more static. Graeme Bartlett (talk) 05:12, 10 September 2008 (UTC)[reply]
The first direct observation of a neutron star in visible light. The neutron star being RX J185635-3754.
The article neutron star states the radius of a neutron star is usually between 20-30 km. However, this image shows a visible neutron star. How is it possible for us to see objects this small so far away in space? (although that's an assumption, maybe it's not that far away) —Cyclonenim (talk · contribs · email) 17:06, 9 September 2008 (UTC)[reply]
It's not the size that matters, it's the luminosity. Stars are generally unresolved in astronomical images. Similarly, you can see the light from my flashlight from hundreds of yards away, even though the filament might be smaller than your eye's resolution. -- Coneslayer (talk) 17:10, 9 September 2008 (UTC)[reply]
Here's some perspective: the largest known star is thought to have a diameter similar to the orbit of Saturn, around 2.8 billion km. The neutron star you linked to is about 450 light years away, and you say 20-30 km diameter for a typical one of those. Let's pretend those two stars are the same distance away from Earth. So using my decrepit memory of trigonometry, I can compute:
So the angle that the neutron star takes up in the sky is indeed *much* smaller than the angle that the big star takes up, as you observed, but consider this: if there were a pinhead being held one kilometer up in the sky it would easily eclipse both stars. --Sean20:08, 9 September 2008 (UTC)[reply]
You must understand that when you see an astronomical photograph with stars in it, the brighter ones will often look bigger, but this is not because the photo is showing their true diameter. It's because no matter how perfect the telescope is, you never get all the photons from the same distant point perfectly focused into the same spot on the film (or digital sensor). With a bright star the scattered photons are sufficient to expose the film and make a slightly larger image. As far as photography is concerned, practically any star is a point source -- only a few of the very largest stars have had their diameter directly measured. The diameters that you see given for stars as well as neutron stars are computed based on theory, not measured directly. --Anonymous, 21:58 UTC, September 9, 2008.
It's also possible (especially with a White Dwarf) that the light you see is being scattered off of dust and gas surrounding the actual object's planetary nebula. That would make it seem a lot bigger than it actually is. SteveBaker (talk) 23:45, 9 September 2008 (UTC)[reply]
In the case of a neutron star, you may be seeing light emitted in it's neighbourhood, generated in the same way as the radio pulse, by electrons accelerated by the spinning magnetic field. We need Sean to calculate what temperature the surface would have to be to get that luminosity, which looks to me to be around 1016 times hotter. Suggesting that the radiation may not be thermal. Graeme Bartlett (talk) 05:18, 10 September 2008 (UTC)[reply]
Core skills of a chemist
Lately I've realized I really have a sincere interest in chemistry. Been reading a little on my own, in my own pace. I've tried college before and it's just not for me, I simply can't stand the boring stuff that inevitably comes with an otherwise interesting topic. Still, I began to think if maybe distance studies - not sure if this concept exists in English, but essentially means studying from home, basically no classes to attend - would work for me. That way I could focus on one semester at a time, so if I felt fed up after one semester I could take a break and just work until I felt motivated again, instead of being on a forced 3-4 year course.
Aaaaanyway, that's just the background. My question is simply this: What are some of the core skills of an aspiring chemist, without which a person would experience difficulties going through an undergraduate level of chemistry education.
I think the main problem you would face would be practical kills. It's not just enough to have the required knowledge, you also have to actually be able to perform your experiments in an actual lab. You have to know that that's just a whole different ballgame. Another problem of course is that the " boring stuff " is often required to understand the interesting stuff. Most chemists I talk to hate quantum physics and higher level mathematics with a passion, yet they agree that it's pretty much required knowledge. Just my two cents PvT (talk) 18:08, 9 September 2008 (UTC)[reply]
I'll second that. Not only is it the case that the "boring bits" are necessary to learn the skills - but also, if you were to become a practicing chemist, a large fraction of your working week would be spent on doing those very "boring bits". If you don't like the boring bits of learning - the odds are very good that you'll hate the job too. It's not common for college courses in the hard sciences to teach things that you won't need to both know - and use on a frequent basis. A similar issue comes about with your desire to take a break until re-motivated...doing that in a daily job would make you pretty unpopular really fast! SteveBaker (talk) 19:01, 9 September 2008 (UTC)[reply]
Hmm perhaps I was a bit unclear about what I meant about core skills. Obviously, even with distance studies I would get lab work, do the boring stuff, and get a degree, which I think were your combined points. What I meant with core skills was, if there are certain ways to think that are valuable, certain ways to look at things, e.g.; does a chemist have to be analytical, have a sense for details, able to see the big picture, be creative, have an excellent working memory, etc etc, the list could go on for very long.
Also, btw, it's been my experience that once you actually get out to work, even the boring parts become enjoyable, SteveBaker ;) ....... Jack Daw (talk) 19:26, 9 September 2008 (UTC)[reply]
That depends a lot on the individual - and (perhaps) the career. I don't know chemistry - but in my line of business (computer programming), it's necessary to document your software as well as design, code and debug it. I know an awful lot of programmers who love the programming bits - but utterly loathe doing documentation. Having to actually write lots of English prose is one of the "boring bits" for those people. So perhaps you don't happen to have any bits of your job that really were boring in the first place...that's the same with me - I'm a programmer who doesn't mind doing documentation in the least. My point is that if you think you just have to get through the boring bits so you can get your degree and they you won't have to worry about it anymore after that...then you're kidding yourself. SteveBaker (talk) 21:04, 9 September 2008 (UTC)[reply]
Aside from the traits you mentioned I would say that a good head for numbers is a big plus. Other helpful skills would include: good manual dexterity, good people skills (you rarely work alone), technical aptitude (you work with machines) and lots of motivation. Note that these aren't requirements, they're just handy traits to have PvT (talk) 20:04, 9 September 2008 (UTC)[reply]
(ec #2) Excellent list. These are all things that are pretty necessary for a bachelor's degree in general chemistry. Of course, there's always sepcialization for higher level degrees. For example, us theoretical/computational people need very good high-level math, and computer programming - but lab skills aren't terribly important. For analytical, good "lab hands" and attention to detail, along with a very good mechanical and scientific knowledge of what instruments you are using, but you won't use much math beyond basic calculus, if that (most of the instruments will do the math for you nowadays).
For me personally, visualization is important, with a healthy dose of memorization ability (but not necessarily a lot). Being able to visualize structures and reactions (in three dimensions), along with how to do things in a lab, is an incredibly helpful skill in almost all areas of chemistry. --Bennybp (talk) 20:23, 9 September 2008 (UTC)[reply]
Help identify this plant
I'm trying to identify a bush/shrub. I'll provide photos if we can't figure this out, but I'll try to describe the plant. It is a medium sized bush (the one I see is probably 4 to 5' all around) which I think is common in the southern United States. At least it can be found in central and south eastern Virginia. The leaves are roughly 3-4" big and a darker green on the top, lighter green on the belly. They have distinctive serrations on the entire edge of the leaf. They feel almost the same as a butter knife. The leaf, when turned sideways, looks almost like lips (elongated oval) that comes to a point at one end. The leaves are thick and waxy. This is also a flowering bush. They are not flowering now so I cannot give much more detail, but I believe they have golf ball sized buds that open up to rather large flowers with lots of pedals that turn brown and fall off. (I could take a picture of one of the brown, dead flowers). Any ideas? Anything else I could look for to help someone identify the plant, or does anyone have some ideas what this could be. Thanks.-Andrew c[talk]18:03, 9 September 2008 (UTC)[reply]
That's a good guess, but not it :) The leaves are not quite that elongated, and the flowers are individual buds, not bunches of flowers (the rhododendron flowers look more similar to bunches of azalea flowers, where the plant I'm talking about has a single large bud and looks like something that may be on a corsage). Plus I'm not sure rhododendron has the serious serrations on the edge of the leaves. Any other ideas? Thanks for the suggestions so far.-Andrew c[talk]18:32, 9 September 2008 (UTC)[reply]
Wait, "all around": what does this mean? If you mean that the circumference is four or five feet, that would be quite reasonable for the peonies I've seen. Nyttend (talk) 20:18, 9 September 2008 (UTC)[reply]
Is the colouring for the attached image likely to be a problem for blue-yellow colourblind people? I know there's a potential problem for red-green people (I myself am one), but I've done the best I can by making the blue/purple and red/green borders as short as possible. Nyttend (talk) 19:40, 9 September 2008 (UTC)[reply]
I'm not blue/yellow color blind, but at the end of the article color blindness there is a link to a website "Colorblind Web Page Filter", which allows you to simulate a webpage for different types of color blindness. Check it out yourself, but for blue/yellow blindness, your picture seems to look fine. -- 128.104.112.147 (talk) 20:36, 9 September 2008 (UTC)[reply]
Actually, there is more than one kind of red/green colorblindness (I think at least three or four). But the thing is that even if you are totally colorblind, you can still distinguish brightness. Yellow is a much brighter color than "computer-screen-primary" blue - so even utterly "every-color"-blind people who can only see in shades of grey will be able to see the difference between primary blue and primary yellow. However, if you'd chosen a brighter shade of blue - or a darker yellow - it would not have been so clear. My son is red/green colorblind - but he can easily tell the difference between red and green - even if they are at the same intensity because his particular variation is that he has a weak red sensor. His problem is between more subtle hues between red and green - and he has a lot of trouble telling red from orange or (to a lesser degree) orange from green. Our article lists at least seven different variations on color blindness - two of those are yellow/blue-related. But the colorblind web page filter is an excellent resource for the normally-sighted to get an idea of what your graphic will look like to each of the different variations. SteveBaker (talk) 20:56, 9 September 2008 (UTC)[reply]
A nice and probably easy MediaWiki hack would be a module that warns you when you upload an image with only a few colors that they're not colorblind-friendly and suggests a substitute pallet with brightness variations. --Sean21:11, 9 September 2008 (UTC)[reply]
Thanks for the various comments: I'd not considered the brightness factor. I'd appreciate the filters, except that (as I noted above) I'm somewhat red-green colourblind (although I'd never read the article, and thus never knew that there were multiple types; I just thought it varied in intensity), so I don't know whether I'd be able to make productive use of them. Nyttend (talk) 05:28, 10 September 2008 (UTC)[reply]
The voice of the NOAA weather radio was previously known as "Paul" (which sounds somewhat like "Mike" from MS TTS). The current one is known as "Tom." I was listening to a local stream of the NOAA All Hazards Weather Radio; who is the voice for this [11] one? The voice sounds like neither "Tom" nor "Paul" (see this [12] to listen to samples).
(Sheepishly) Yes, but also from the temperature, humidity and steady 15 kt wind and it was the middle of August. But you know what Mark Twain didn't say?. (I do remember his story about the S.F drunk who froze to death under a blooming rose, though, don't I?) Saintrain (talk) 01:50, 10 September 2008 (UTC)[reply]
I clearly remember that a few years ago, I somehow missed an occultation I was planning to time and later tried to determine whether I could have seen it. I found a site that listed the temperature, cloud cover, and other conditions for every hour. I can't remember how far back the archives extended or whether they covered any city except my own (the Greater Toronto Area). I also can't seem to find it again. --Bowlhover (talk) 04:20, 10 September 2008 (UTC)[reply]
Ah, another datum for my planned great-identity-stealing machine, Bowlhover is a Hogtowner! Please tell, haven't you just had a record-setting amount of rainfall in my dear departed province? Franamax (talk) 06:15, 10 September 2008 (UTC)[reply]
Thanks. The METARS information link available at the bottom of the weather underground page gives the sky condition as scattered cloud and broken cloud, but not overcast.
It's possible that it's the day the person was born/married/parents married/whatever. I can imagine the phase of the moon will mean something to those who believe in astrology. I've never heard of anyone caring about what the weather was like though Nil Einne (talk) 11:42, 12 September 2008 (UTC)[reply]
Global Warming
I've been thinking: wouldn't inducing a rapid growth of algae or something similar in the world's oceans (by putting large amounts or iron or something similar) make considerable progress in reducing the carbon dioxide content or the atmosphere? Before you ride me off, I think I remember reading on Wikipedua (I can't find the article) that a certain algae, because they were found in such large numbers, caused an Ice Age.
The problem is that algae pretty much shut out all of the other lifeforms - so sure you'd maybe reduce CO2 - but maybe you'd also kill off all of the fish. The problem with all of these "radical" solutions is that we don't have a good enough understanding of the consequences of doing them. It's very likely that we'd make matters much worse. SteveBaker (talk) 23:39, 9 September 2008 (UTC)[reply]
I see, but according to the article it is still in the experimental stage. However, we could already see the effects of the human induced algal blooms.--Lenticel(talk)23:51, 9 September 2008 (UTC)[reply]
It is experimental because we don't yet know all the effects, such as whether the carbon actually gets sequestered to the ocean floor, and what the nasty side effects might be, such as creating anoxic regions, as Steve notes. If you email me, I can send you a few papers and articles from Nature. Franamax (talk) 00:05, 10 September 2008 (UTC)[reply]
Hello. I'm a high school student interested in physics and have just read about the concept of antimatter. Unfortunately I got lost very quickly in the preface of the article on this subject and am having real difficulty grasping in my mind the concept of antimatter. could somebody explain it very simply to me, perhaps with a helpful illustration? 79.75.199.175 (talk) 23:54, 9 September 2008 (UTC)[reply]
Have you read antiparticle? I think we're going to need to know what it is that's confusing you particularly, otherwise we're going to end up explaining it the same way as the articles. --Tango (talk) 23:56, 9 September 2008 (UTC)[reply]
Well as i understand it antimatter is the opposite of matter, so one would assume antimatter does not have mass while matter does. However i'm not sure if particles such as photons which have no mass are considered antimatter so i might be wrong in my understanding here. If matter is "stuff" then is antimatter is "non-stuff" which also takes up space or what? 79.75.199.175 (talk) 00:23, 10 September 2008 (UTC)[reply]
Matter has many properties, and antimatter certainly doesn't have the opposite property of each of them. In particular, it has mass. --Sean00:32, 10 September 2008 (UTC)[reply]
No, other quantum numbers such as spin and colour charge are also reversed in an antiparticle. If only the (electric) charge were reversed then the antineutrino would be identical to the neutrino. Gandalf61 (talk) 10:59, 10 September 2008 (UTC)[reply]
There is no real difference between matter and antimatter overall (well, there might be if you get to really complicated stuff, but that's not important to start with), there is only a difference when you compare a particle with its antiparticle. For example, some matter is positively charged (eg. a proton) and some is negatively charged (eg. an election). Likewise, some matter is positively charged (eg. a positron [anti-electron]) and some is negatively charged (eg. an anti-proton). So, it's not that matter has one property and antimatter has the other, that only applies for a particular particle/anti-particle pair. --Tango (talk) 00:38, 10 September 2008 (UTC)[reply]
Matter is a poorly defined word. It usually means anything that has mass and takes up space. By this definition, antimatter is not the opposite of matter; it's just a confusingly-named kind of matter. (And, for that matter, antiparticles are not the opposite of what we usually call particles; they're just confusingly-named kinds of particles.) --Allen (talk) 00:53, 10 September 2008 (UTC)[reply]
well, last night i went to an italian restaurant and ate antipasto followed by pasta, and there is definitely a vast quantity of energy being liberated as they meet. Gzuckier (talk) 16:41, 10 September 2008 (UTC)[reply]
In sequencing of DNA, reads will sometimes have .b1 and .g1 for the forward and reverse primers when producing amplicons. Does anyone know why the letter b is associated with forward and why g is associated with reverse? Thanks. --Rajah (talk) 02:39, 10 September 2008 (UTC)[reply]
No one seems to have an answer, however this is what I have found: There are primers called A1 A2 B1 B2 C1 C2 D1 D2 E1 E2 F1 F2 G1 G2, with the 2 primer for use on the alternate strand to the 1 primer. Also different primers are indicated by the same symbols by different researcher. So your primers must be in the context of some system or commercial product - can you say which one? Graeme Bartlett (talk) 21:55, 11 September 2008 (UTC)[reply]
Carbon dioxide sequestration
There is a lake somewhere inside a volcano cone that sequestered CO2 coming from the volcano at the bottom of the lake do to the temperature and pressure at the bottom. A tremor or some other disturbance released the gas and its spread over the slopes and kill people and livestock. How much risk of this is there in the man-made sequestration of CO2 in ocean bottoms and oil fields and the like? —Preceding unsigned comment added by 71.100.10.144 (talk) 04:20, 10 September 2008 (UTC)[reply]
That was Lake Nyos, in case someone wants to read more about this. --Anonymous, 20:08 UTC, September 10, 2008.
The ocean bottom is risky, if the super carbonated water comes to the surface it will foam up in a big way. ANother risk is acidification of the water with dissolving of shells and bones of sea creatures. With underground storage, it presumably will be pumped back into a gas well that is reasonably well sealed, but as you say a rupture could release the gas again. Natural kinds of these ruptures can crack at the rate of about one kilometer per second and erupt at the surface in a special kind of explosive volcano as a Kimberlite pipe. Graeme Bartlett (talk) 05:30, 10 September 2008 (UTC)[reply]
A) The ocean already has ~50 times as much dissolved carbon as the entire atmosphere, so it is implausible that you could pump enough carbon into the ocean to really pose a threat due to gaseous discharge (i.e. Lake Nyos) B) The key word for Kimberlites was "volcano", their source needs to be at least 1000 C. You can't really compare a capped well to a deep, fast moving flow of molten rock and dissolved gas. Dragons flight (talk) 05:48, 10 September 2008 (UTC)[reply]
The issue with the ocean is putting too much in too little water. At pressures of 100 bars you can dissolve plenty of carbon dioxide. Cool carbon dioxide breaking out from a well would be dangerous to humans and animals due to suffocation. It does not need to be heated to 1000 degrees. Carbonatites can be as low as 600° degrees. By the way does anyone know how to get the degree symbol that used to be down the bottom of the edit box? Graeme Bartlett (talk) 05:56, 10 September 2008 (UTC)[reply]
My understanding of ocean storage is that the CO2 will be simply pumped into the ocean depths, rather than stored in the sub-floor as in above-ground CCS schemes. This avoids the catastrophic-release problem, but presents others such as the massive formation of carbonic acid and uncertainty on the speed of return to atmosphere.
Hey thanks that ° works, my menu selection was on wiki markup! To work out the risk there may have to be a proper risk assessment looking at how many people are killed, economic loss, non productive use of energy etc. The lowest risk option may be to put the carbon dioxide in the air. There would not be enough old oil and gas wells to take all of the power station emissions of CO2 in any case. I much prefer the real soylent green method. Another way is to reproduce the azolla event that stripped the atmosphere of carbon dioxide. Also the end of the cryogenian was a time when huge amounts of carbon dioxide were removed, but this cannot be done now. Graeme Bartlett (talk) 06:14, 10 September 2008 (UTC)[reply]
Actually, estimates suggest there are enough geologic repositories to eat all emissions for 100 years or so. Doing so would require drilling new wells, usually into deep (2+ km) saline aquifers, but that's not too big a deal. We annually remove ~3×1012 m3 of natural gas from the Earth. We have about 20×1012 m3 of CO2 per year to store. The room exists, at least for a while. (It shouldn't be a shock that those numbers are on the same order of magnitude since natural gas is one of the three principle fuels used to create CO2.) You seem to have a lot of fear and doubt, but I suspect you've never really looked into the technology in serious way. It's not as scary as you seem to imagine, and has a lot of potential for near term mitigation. Dragons flight (talk) 07:14, 10 September 2008 (UTC)[reply]
Well, one of the sources of FUD is that these solutions will presumably be provided by private corporations, who will sell their sequestration services for a profit. And when their CO2 reservoir fails (especially if they have over-pressurized them by the 20/3 ratio you allude to above), there will be human deaths near the failure zone, there will be no corporate assets left to claim in the damage suit other than the broken CO2 storage reservoir, and all the CO2 will be back in the atmosphere. Yeah, there is some doubt there. But whatever, lets forget about that old energy conservation idea - that was hippy talk anyway. Franamax (talk) 07:25, 10 September 2008 (UTC)[reply]
That 20:3 ratio (as scarey as it is) is nothing like the right ratio though. It assumes that we can efficiently remove the CO2 from all of the other gasses that come out of the power station (or whatever). Since the air used to fire the power plant is only 1/5th oxygen - and the rest nitrogen, most of what comes out of the power plant is nitrogen. If you try to pump all of the exhaust gasses into your underground store then the ratio isn't 20:3, it's more like 100:3. Separating out the CO2 from the nitrogen is difficult and requires an enormous amount of energy...which in turn means generating even more CO2 than we do now. Conservation and renewable are by far the best route. SteveBaker (talk) 18:13, 10 September 2008 (UTC)[reply]
Actually, removing CO2 from a vapour stream is relatively straightforward, at least in gas processing it's done with an amine absorber. I have no great idea on the energetics though, nor what size of vessel you would need to process the output from a power station. Or if that's even the scheme one would use at a power plant. Also, amine contaminates easily, is a high-foaming service, and is deadly poisonous. But anyway, it selectively removes CO2! Franamax (talk) 03:39, 11 September 2008 (UTC)[reply]
Or are you talking about the Compact Muon Solenoid in the LHC? Muons are emitted from the experiemnts or formed by decay of other particles, and can penetrate further and last longer than most of the other high energy particles. These can be detected further out form the core. Look at this for how this works and what it is used for. Graeme Bartlett (talk) 05:47, 10 September 2008 (UTC)[reply]
MSN just a a front-page piece about how the LHC might destroy the world (not kidding). Times like these I have an even lower opinion of the media in general.... --mboverload@07:25, 10 September 2008 (UTC)[reply]
it's all part of cern's plan. by creating the web, they led to google; so that when the earth gets destroyed by a black hole, a digital archive will still exist. Gzuckier (talk) 16:37, 10 September 2008 (UTC)[reply]
i bought a dual voltage hair dryer for travelling. it has a black switch on the handle where it allows you to choose 115V or 230V by turning it w/ a screw driver or a coin. where should it be when in the US???? —Preceding unsigned comment added by 68.97.36.155 (talk) 06:34, 10 September 2008 (UTC)[reply]
Also note that the 115V setting will be correct in bathrooms of many hotels in Europe that cater to Americans. Just look for the "110" or similar label and U.S.-style plugs. I've been surprised how common this is.--Scray (talk) 10:29, 10 September 2008 (UTC)[reply]
absolutely correct. you will probably not see a 220 volt outlet during your travels in the US and Canada, and if you should perchance find one, it won't accept the normal north america plug which presumably you have for your shaver. Gzuckier (talk) 15:20, 10 September 2008 (UTC)[reply]
Only place one is likely to find anything other than 115V in US houses is sockets specifically designed for heavy-duty appliances (electric clothes dryer, electric stove, air conditioner). And the sockets are usually shaped differently so that you can't plug the "wrong" thing (something designed for 115V) into them. DMacks (talk) 16:20, 10 September 2008 (UTC)[reply]
I thought the 220v outlets in the US were some kind of funky three-phase arrangement though. I don't think you could plug a euro-style 220/230/240 volt gadget into one of those even if the plug did fit. There are also concerns over the frequency shift (60Hz in the USA, 50Hz in Europe) - most devices don't mind but my 110v laptop charger severely overheats in Europe when I plug it into my 240v to 110v converter widget. I believe that could only possibly be due to the frequency change. SteveBaker (talk) 17:56, 10 September 2008 (UTC)[reply]
As a general rule, anything with a transformer or motor can be used on 60Hz electricity if it was designed for 50Hz, but you can't go the other way around: the magnetic field will saturate, and will stop being an inductive load and start being a short circuit. --Carnildo (talk) 20:32, 10 September 2008 (UTC)[reply]
Standard 240 V (not 220 V) outlets in North America deliver two opposite phases of 120 volts plus neutral. This is not 3-phase power, but it does mean that there are two live slots. A European device would expect one live and one return wire, like a North American 120 V outlet, so the regulations would be different regarding safety insulation. (This is all in addition to the safety ground (earth) wire.) Outlets for 3 phase power also exist but are not found in homes. Just to further confuse things, some places in North America use two phases of 3-phase power, thus delivering 120 V between one phase and neutral but 208 V between two phases. This is most common in larger buildings, including some apartments.
As to frequency, resistive applications (heaters, traditional light bulbs) don't care, but transformers do care (as Carnildo says), some types of motors do, and some types of electronics do. If the hair dryer is dual voltage then very likely it will also be marked as taking either 50 or 60 Hz, in which case there's no problem, but you may notice the blower motor running faster in North America. --Anonymous, 20:40 UTC, September 10, 2008.
Ah, so that's why so many things in industrial things are 208V! Always struck me as a weird number to get from the same power distribution system that gave 120V. DMacks (talk) 00:18, 11 September 2008 (UTC)[reply]
Star vs. delta 3-phase wiring
You get it when your three-phase system is wired in the star-configuration. 120V from the centre to the outside, between outside points = 2 x 120V * sin(120) (the voltages at each "point" of the star are 120 degrees out of phase). I'd link an article but I can't find any good links for delta/star three-phase - and I've been burned enough lately that I'm not going to complain about it either, someone will just point out my spelling mistake! :) Franamax (talk) 03:23, 11 September 2008 (UTC)[reply]
hello wikipedia,
Once of the (many) reasons i find americans endlessly fascinating is that they don't use kettles. As work is going really slowly today, i thought i'd just ask, if you gyus wanted to boil water for cooking (pasta, potatoes etc) what would you do, just put cold water on the stove and heat it up from scratch? Does this not drive you crazy? thanks217.169.40.194 (talk) 08:18, 10 September 2008 (UTC)[reply]
An electric kettle can boil the water faster than a gas stove. Its even quicker if you heat a third of your water on the flame, and two thirds of the water in a kettle and then combine them. But simpler if you don't use a kettle at all. Do Americans call a kettle by a different name? Graeme Bartlett (talk) 10:09, 10 September 2008 (UTC)[reply]
I'm the American child of East-coast American parents, and we've always had (and called it) a kettle. Same for my wife, a native of California. I think someone is over-generalizing here. Perhaps we need a WP:RS.--Scray (talk) 10:34, 10 September 2008 (UTC)[reply]
Non-use of kettles is fascinating? I can assure the OP that some, possibly many, Americans do use kettles. We have the plain kind that you plop onto the stove; we have the electric kind. In bygone days, people left filled kettles on wood stoves or coal stoves to provide some humidity in the winter. (More recently, people bought cast iron kettles to do the same in a retro kind of way, only to learn that cast iron isn't a great idea for holding water over long periods of time.)
My guess would be that most people here cook pasta or potatoes by boiling the water in a large pot on the stove (like a stockpot or a large saucepan). A related guess is that many kettle-users drink tea; people who drink mainly coffee will tend towards coffeemakers.
I agree with the Tea assumption. My aunt lives in Italy, and had to get a kettle shipped over from Ireland to make the sacred brew. In Italy, being very much a coffee country, kettles were nearly impossible to obtain! Fribbler (talk) 12:24, 10 September 2008 (UTC)[reply]
As for being driven crazy, we have so many options here that the agony of waiting for pasta water to boil doesn't enter into it. (By "kettle" I'm referring to a vessel with a spout -- e.g., teakettle. Another usage is for a large, open vessel, as in "a different kettle of fish," whence also "kettledrum." Without that kind of kettle, there'd be no cartoons with explorers or missionaries being prepped for dinner.) --- OtherDave (talk) 10:56, 10 September 2008 (UTC)[reply]
It's significantly more energy efficient to use a kettle, which is something Americans have never been too concerned with (just look at average fuel consumptions of cars in the US compared to Europe, say). That may have something to do with the different practice on the other side of the pond. --Tango (talk) 11:34, 10 September 2008 (UTC)[reply]
I agree with OtherDave. For one, I would call it a tea-pot or tea-kettle. Simply saying "kettle" needs context to know whether you meant for making tea or if you meant something that Elmer Fudd would boil Bugs Bunny in for stew. For two, everyone I know would likely use a large sauce pan or pot to boil water in for potatoes or pasta. And lastly, I would put a lid on the pot in order to save energy and time. Dismas|(talk)12:25, 10 September 2008 (UTC)[reply]
Electric kettles are very handy for a cuppa. I assumed that the reason they were so fast is the 250V. What is the wattage of a UK e-kettle? Saintrain (talk) 12:34, 10 September 2008 (UTC)[reply]
To avoid confusion, note that (in the UK at least) teapot and kettle (never heard it called a "tea-kettle") are different objects. You boil water in a kettle, then pour the boiling water into a teapot together with tea leaves or tea bags to make tea. Gandalf61 (talk) 13:06, 10 September 2008 (UTC)[reply]
When you say "kettle", are you referring exclusively to a "teakettle"? (With a spout and everything. Probably a whistle, too.) Because that's all the word "kettle" means in USA. I notice that the article mentions that it could have a wider meaning in the UK.
For completeness, what would be the pasta making procedure in, say, England? Would you pre-boil some or all of the water in a teakettle before transferring it to a pot? That seems like a good amount of extra effort. APL (talk) 13:12, 10 September 2008 (UTC)[reply]
As an energy-conscious German, yes, I pre-boil water electrically before filling into a pot, be it for rice or pasta cooking. You'll do that too as soon as you pay as much for energy as we here do. --Ayacop (talk) 13:44, 10 September 2008 (UTC)[reply]
I did manage to find a store in Texas that had electric kettles - they aren't easy to find though. It's really crappy by UK standards - but it works. IMHO, the way you heat water depends on the amount. For small quantities (eg to make a cup of coffee), I use the microwave oven. It's faster than a kettle and vastly more energy-efficient. For medium sized quantities (eg to make four cups of coffee), I use our Texas kettle. At those quantities, it's more energy-efficient than the microwave and faster too. For larger quantities, I use the stove-top and a saucepan - more for speed than for energy efficiency. If I had a larger kettle, I'd use that. SteveBaker (talk) 13:37, 10 September 2008 (UTC)[reply]
The Utah teapot - very important to computer graphics geeks!
When you say "tea kettle" in the USA, you're typically imagining an approximately hemispherical vessel with a flat bottom that you set on top of the stove. When we say "kettle" in the UK (they aren't "teakettles") - we know about the US thing - but we're more likely to be thinking of a large cylindrical pot with an electric heating element in the bottom that can boil a couple of pints much more quickly than you could ever do on the stovetop - and with better efficiency too. The fancy modern ones have dual elements for greater efficiency and little float gauges on the side to indicate how full they are. They typically have "curly-cord" power connections (like a short telephone cord) for kid-safety, auto-shutoff when they boil, maybe have a beeper to replace the old whistle. They are sophisticated, highly evolved machines - compared to an American tea-kettle: think "Ferrari versus Trebant". A "teapot" is a (typically) ceramic pot with a spout and a lid in which the tea is actually brewed - you don't ever heat the water in a teapot.SteveBaker (talk) 13:47, 10 September 2008 (UTC)[reply]
Some of us Americans might be more likely to refer to the electric water heating apparatus as a "hot pot," as can be seen by the category name in this Amazon listing. Personally, when I need to heat water for tea, I use the quintessential Revereware kettle; if it was good enough for both my grandmothers, it is good enough for me. Personally, I had a hard time searching for a tea pot that I liked, but that's another story. --LarryMac | Talk14:16, 10 September 2008 (UTC)[reply]
The Revereware kettle looks like the sort of thing one would take camping. A few people in Britain still use such kettles on a gas hob at home. DuncanHill (talk) 15:33, 10 September 2008 (UTC)[reply]
The one and only electric kettle we've ever found here in Texas looks pretty much exactly like one of those - except it has three little rubber feet underneath and a wire coming out of the back! SteveBaker (talk) 17:38, 10 September 2008 (UTC)[reply]
I've used an electric kettle in the UK to boil water, and it does a fine job on the 240 volts available in the wall outlet. But in the US the voltage is half as much, and the appliance amperage is usually limited by the 15 or 20 ampere rating of the circuit, so it takes a long time to boil water with an electric kettle. Looking at some adverts, the UK kettles seem to have a 3000 watt rating and the US kettles only a 1500 watt rating. A stovetop burner seems to apply more energy to the water and get it boiled faster. Of course someone could have a 240 volt outlet installed in the kitchen for the electric kettle, but this would be very unusual outside a restaurant. 3000 watts would be 10,240 BTU per hour, and stovetop range burners can be had with 15,000 BTU per hour and higher rating. Granted, the electric kettle should apply the energy to heating the water more efficiently than a kettle setting on a range burner. A microwave might have just a 1000 watt rating. Edison (talk) 14:58, 10 September 2008 (UTC)[reply]
What you're missing with the microwave part of that is that the microwave only has to heat up the water and some kind of container (which in many cases is the container you're going to use for the drink anyway). An electric kettle has to heat up that large metal element too - and when you pour the water out, a lot of heat energy remains in the kettle itself. That's why the microwave is a more energy-efficient solution. Also, if you pour the water out of the kettle into a cold ceramic cup - then the cup cools the water down. With the microwave, the cup is also heated - but that energy isn't wasted. The stovetop is even less efficient for much the same reasons - but also the thermal connection between the heater element and the water inside the pot is a very poor one compared to having the electrical element immersed directly into the water...hence yet more energy goes into heating up the air and the metal stove top. That's why the microwave is the most efficient way to heat water (and also the fastest if the quantities are small) - the electric kettle comes second and the gas/electric stove-top is (by far) the worst.
Yet another problem with kettles and stoves is that while the water is heating, oxygen and nitrogen come out of solution and stick to the sides of the container. As it comes close to boiling, steam bubbles do the same thing as the water closest to the heat source reach boiling point long before the rest of the liquid. Those bubbles are extremely good heat insulators and prevent much of the heat transferring into the liquid - allowing the heating surface to (uselessly) get hotter than 100degC. Microwaves (by their very nature) only heat the water itself - so 100% of the energy goes into the water. You might think this is a negligable effect - but it's really not - and I can prove it (albeit indirectly)...
If your car engine is overheating, you can sometimes get it to run cooler by flushing out the antifreeze and replacing it with plain water. That's because plain water conducts heat better than ethylene glycol. However, this steam-bubble formation issue strikes because the boiling point of water is lower than the glycol/water mixture and the water may boil as it passes through the engine block causing localised hot spots that can actually ruin your engine...maybe even crack the block. There is stuff you can buy called "Water wetter" that lowers the surface tension of the water and raises it's boiling point WITHOUT reducing it's thermal conductivity that fixes this problem entirely.
I agree that the lower mains voltage/current is the likely reason why electric kettles aren't popular over here though...although I have 240 volts going to my cooker - it wouldn't take much to wire up a UK-standard 3 pin plug...hmmm - it's tempting!
UK mains is generally fused at 13 amps, so if you have up to 20 amps that compensates for the lower voltage quite well. 115V at 20 amps gives a maximum of 2.3kW, plenty for boiling water (it's the cheaper end of the UK kettle market, but it'll do just fine). Rather than talking about all these meaningless numbers, let's try some meaningful ones - it takes about a minute to boil a couple of pints in my kettle (far less to boil a mug full for a cup of tea/coffee). How long would it take on your hob (or "stovetop" or whatever you call it)? --Tango (talk) 15:19, 10 September 2008 (UTC)[reply]
Just pointing out the UK mains electricity has been delivered at 230 volts rather than 240 volts for something like the last 10 years. To harmonise European standards, those continental supplies that were on 220 volts have been or are in the process of being upped to 230 volts. I seem to remember some spurious talk at the time of the changeover that it would affect the economy because it would take longer to boil a kettle and people would take longer tea-breaks. It would also make you late for work because it would take longer to make toast. Jooler (talk) 15:21, 10 September 2008 (UTC)[reply]
Well, it's 230V +/- 10%, so that's anywhere between 207V and 257V, so the change from 240 to 230 is less significant than the natural variation anyway, so I don't think you can use that as an excuse when you're late for work! --Tango (talk) 15:49, 10 September 2008 (UTC)[reply]
Hmmm - I always thought the change was not one of the actual voltage provided - but a change from quoting the peak-to-peak voltage to talking about the RMS voltage in order to comply with Euro measurement standards. I guess I'm wrong on that score then! SteveBaker (talk) 17:46, 10 September 2008 (UTC)[reply]
I'm a (naturalized) American, so I'll just answer the question as a data point: if I want to boil water for pasta, I take my 4 dogs' communal water bowl, run the hot water tap into it until the water is hot, then fill a thin-metalled pot with the hot water, put some salt in, and put it on my gas range. It's usually boiling within a couple of minutes. --Sean00:13, 11 September 2008 (UTC)[reply]
You cook with water from the hot tap? Isn't that supposed to be a really bad idea because it's been sitting in a warm tank and pipes for god knows how long? Boiling it may kill off the vast majority of germs, but it won't remove anything that's dissolved in it (hopefully you don't still have lead pipes, or that could be really nasty!). --Tango (talk) 14:14, 11 September 2008 (UTC)[reply]
Most houses in the US use either copper or plastic for the pipes, and you're supposed to keep the hot-water tank at 140F or above, hot enough to kill anything dangerous. --Carnildo (talk) 21:08, 12 September 2008 (UTC)[reply]
boiling a cup of water
on a related note, whatever happened to those little plug in one cup heater uppers? (let alone the immersion heaters) i can't find any for 110 volts any more, only 12 volt car ones. i'm toying with hooking one up with an old gel cel 12 volt battery and a wall wart, just so's i can get a cup of hot water for beverage purposes at work. Gzuckier (talk) 15:26, 10 September 2008 (UTC)[reply]
This [18] would do for making instant coffee, but as it does not actually boil the water is unsuitable for making tea. I would add that as one can buy a perfectly serviceable ordinary electric kettle for a fiver, it does not look like good value for money. DuncanHill (talk) 15:40, 10 September 2008 (UTC)[reply]
yeah, but i'm looking for something highly unobtrusive. otherwise the Corporate Preventers will spot it and break into one of those "whatever it is, I'm against it!" routines that they do so well. that's why i've been holding off on the battery/12 volt mug approach.Gzuckier (talk) 16:31, 10 September 2008 (UTC)[reply]
Somewhere on the interweb I saw a USB-powered coffee maker - the USB charges a battery inside that actually heats the water. I'm not sure that helps the issue with the Corporate weenies being a pain. It would be kinda neat on a back-packing holiday though: "I sure could use some hot coffee right now."..."Sure, I'll go grab my laptop and be right back!". SteveBaker (talk) 17:46, 10 September 2008 (UTC)[reply]
Speaking of which this was a great solution for us to run a USB hub in -25 C ice core lab. It's hard to find cheap, cold-rated usb hubs, but you don't have to if they have a built-in heater. ;-) Dragons flight (talk) 17:57, 10 September 2008 (UTC)[reply]
<soapbox warning>I just want to say that I haven't had so much fun since I first came to Wikipedia. Even with the U.S. / U.K. differences, none of the armed-Talmudic screeds about those with disagreeing opinions.</soapbox>
I was born in Canada but raised in the States, and my parents have always had a (non-electric) kettle (for the boiling) and a metal teapot (for steeping the loose tea leaves and leaving on the stove with just a smidgin of heat).
I think the energy-conscious comments are apt; we're still bellyaching about gas costing $3.50 a gallon.
You can find electric kettles (other than the venerable Hot Pot) here, but you have to look hard, or else go to Canada.
I agree completely with the need to have boiling water for tea (and with the need not to have the word "Lipton" within 500 yards), which is why visitors to the U.S. who are in their right minds never order tea, except perhaps in some non-chain college-town coffee boutique. --- OtherDave (talk) 13:21, 11 September 2008 (UTC)[reply]
UK Spiders
What is the name of those orangey-brown and white spiders that become so prevalent in the UK on cold September mornings? Little blighters were all over my car this morning... sparkl!sm hey!08:57, 10 September 2008 (UTC)[reply]
Gynaecology is a medical speciality. So the course you would be taking at third level is medicine. As I understand, in the US (you said high school, so I'm guessing you live there) medicine is a graduate-entry course in that you must first have a relevant degree in say Biology first before you can do medicine. So Biology and Chemistry would be the subjects best suited to pursuing this first degree. Fribbler (talk) 12:14, 10 September 2008 (UTC)[reply]
If you truly want to be any sort of specialist, this is a suggestion that I've seen work with many people since I've been working in the medical field:
Start volunteering at your local hospital now. You will be doing junk work with no (or very little) pay. But, you will be around doctors and get used to hearing medical-speak. You may realize that you hate the profession and change your mind.
Take all the biology and physics that you can in High School. If yours is like mine was (white-trash redneck tiny-town school), you'll have to take classes at a local community college instead of high school.
By your senior year, pick the medical schools you want to go to. They will have "sister colleges" that offer the pre-med courses. Now, you know what undergraduate colleges you want to go to. You can work on getting into them.
As an undergrad, continue volunteering at the medical schools you want to go to - including applying to do any work you can in research projects. You'll get paid for that work. The goal here is to get your name known with as many people in the school as possible.
As you near the end of pre-med, study and study and study for the MCAT. Your score on the MCAT will be a major factor into getting into med school as well as getting free funding for the school.
Assuming you do well on the MCAT, you'll be accepted to the medical school. You'll be a general medical student (specialist courses don't matter at the beginning). Try to get an advisor that is in the field you want to work in. He or she will guide you through the courses you need and possibly get you into a volunteer position in the field.
From that point, you are set - do well in your classes, keep volunteering, and all those years of working for no pay will finally pay off as you will have the education and the years of experience to bubble up to the top of your class and get a good job anywhere you like.
Keep in mind that that is only one way to do it. You could just have rich parents to donate a building to the medical school in exchange for a degree. -- kainaw™12:48, 10 September 2008 (UTC)[reply]
Also: you're in high school, so please forgive me if your intentions are pure, but, speaking as a one-time high school boy, let me advise you that if you're thinking that this is a good way to see lots of vaginas, I can't tell you how wrong you are. Under no circumstances should you (or anyone else, for that matter) click on this link: Google image search for "diseased vaginas". --Sean01:10, 11 September 2008 (UTC)[reply]
physics
whether man can run fast or slow on moon.Plz explain with respect to on earth
Not fast in short distances, because each step takes you away from the surface for too long, so you can't accelerate fast enough. Long distance is different because no friction happens while in the air, but I'd guess it difficult to accelerate further when already at high speed. --Ayacop (talk) 17:24, 10 September 2008 (UTC)[reply]
An additional problem for lunar hiking is one of mass. An astronaut must haul around a substantial portion of body mass in life support equipment. While the weight of all this is fairly low (with the 1/6g at the lunar surface), its mass and inertia is unchanged. It's much harder to start, stop, or change directions on the moon than on Earth. — Lomn18:00, 10 September 2008 (UTC)[reply]
An Earth-bound similarity is the high-speed cars that try to break ground-speed records. The ones that use tires as propulsion have to deal with the friction between the tire and the ground. If they gun it at the start, they spin out and don't move much. That is a lot of wasted fuel and energy. So, they start slow and build up speed. At high speeds (around 300mph), the tires no longer have the ability to push the car forward. They just spin out if any attempt to accelerate is made. So, the car has reached a top speed, not based on the engine, but based on the tire's friction. Translate that to a man on the moon and you have the situation explained by Ayacop. -- kainaw™18:03, 10 September 2008 (UTC)[reply]
No (provided the area around the black hole is a vacuum). Gravity can affect the trajectory of light but not its speed. — Lomn17:56, 10 September 2008 (UTC)[reply]
Which is a "yes." I agree that the black hole does not change the speed at which light travels, but remember that a change in direction, even at constant speed, is also an acceleration. Chuck (talk) 21:24, 10 September 2008 (UTC)[reply]
If you're standing somewhere a significant distance from the black hole (as I would hope you are, seeing as I'm on the same planet as you!), you won't be able to see any light approaching the black hole, since you would need to be inbetween the light and the hole. --Tango (talk) 14:19, 11 September 2008 (UTC)[reply]
CERN AL-Zanders' dropping some mighty LHC yo!
That's science-ghetto-geek talk for my own reference of one: CERN, and two: the Large Hadron Collider.
Question: Will this effect the way we make toaster ovens?
Meaning, do we the little people of science know the uses this collision will do for us in the proletariat section?
Not the Little-Black-Hole-Bang talk, but on a slippery slope, could this be a stepping on a butterfly, as in the Effet de Papillon?
Wikipedia is not a crystal ball. It cannot be used to tell the future. If you are asking for references (as this is a reference desk), a search of periodicals at all three local universities shows absolutely no hits on articles containing both "hadron collider" and "toaster oven". -- kainaw™17:56, 10 September 2008 (UTC)[reply]
instead of mountain climbing you can go wind surfing on a lake, the positive side, for the average Joe, the problem with rising sea levels is solved.Mion (talk) 18:48, 10 September 2008 (UTC)[reply]
So, we split the atom, then blew up folks with some a-bombs. I'm just saying, what are the negatives and positives, most likely the negatives that cripple mankind will be extorted first. Considering history. Ok, simply: We collide some Particles. Okay., and the point is??? That's the question. The answer I take from the round abouts is, "We'll all see when it happens." And that's an alright answer. So the premise is, we can do something we have never done before, to our collective memory of 4000 years, but we don't really know what we're doing. And that's ok. But if any scientists here actually know some simple E=mc2 answer, Energy equals Mass, what of it? Is this to understand Mass more? Understand Energy? Yes, we are Technological here, yes, we have some smart answers w/ or w/o sarcasm. But brass tacks: What are we doin' here with this LHC? 'Explain your answer to a 12 year old.' <--true sciences. Please. Cheers, --i am the kwisatz haderach (talk) 19:19, 10 September 2008 (UTC)[reply]
LHC is a tool that will be used to examine subatomic particles and the forces with which they interact, and to study some areasa of physics where certain theories were not testable experimentally until now. It's a basic-science thing, not an engineering/applied-science "build a better mousetrap" goal. One could certainly speculate about new devices that could be built using whatever exotic stuff they find, but that's...speculation, even on the part of those actually doing the experiments (who no doubt had to somehow justify this hugely expensive special-purpose gadget to numerous governments and scientific agencies). DMacks (talk) 19:29, 10 September 2008 (UTC)[reply]
It's unlikely the LHC will have any benefits to individual consumers, if that is what you are asking. It is likely that the biggest overall benefit to society will be in the form of keeping a lot of scientists on the payroll in general, and of those scientists a certain number will eventually come up with something helpful or practical. Many of the scientists will gain in prestige from their work with the LHC, which will help them get future funds, and the whole cycle continues. There's always the rare, rare chance that something will directly come out of work like this but it doesn't happen very often, and I don't think anyone's expecting it to happen here. Big Science is as much about creating a Big Infrastructure as anything else, which can serve as an end to itself. That being said, there's a strong argument for, "surely we could spend the money better elsewhere" which might be true, though frankly most governments burn through money in the most inefficient ways anyway, and the amount of money spent on the LHC is a drop in the bucket. --98.217.8.46 (talk) 19:40, 10 September 2008 (UTC)[reply]
Thanks much. Digression: There's a really cool video game at the time, late 90's-Early 00's(Early Zeros), that had this Science David Banner-like guy going into the CERN or CERN like particle accelelerator. Opens a mini-black hole, another dimension of time and space, then you go about on this adventure. End of game you come back chasing a villian, I think you end up blowing him up, more imploding him up with the facility. I forgot the name of the game, but it was fun. And the first time I heard of a Particle Accelerator. And I think there was a Jean-Claude Van damme movie with one in it. Reading more about it I see the basic-science questions of MORE INFO on the DarkMatter/Energy thing, Matter/Antimatter, GUT, etc. GO SCIENCE!!! --i am the kwisatz haderach (talk) 19:44, 10 September 2008 (UTC)[reply]
In case the 12 year old doesn't follow all that, the idea of the Large Hadron Collider experiment as I understand it is to whip some incredibly tiny particles up to incredibly high speeds and then let them crash into each other, to see what happens and perhaps learn something about the universe.
The experiment is not considered dangerous because the amount of energy involved in each "crash" is not quite enough to run a 60 watt light bulb for a second.
It's testing a scientific theory. Science isn't just going around saying "what if?", it's going around saying "why's that?". Once there's an understanding of "why" then there can be predictions of "what else".
There are precise predictions of what's going to happen during the collisions, based on the current (prevalent) model of how the world works. The predictions will be borne out, confirming the model, or they won't, providing new insights into how the world works. If confirmed, researchers will have greater confidence in the predictions that will lead to engineering advances.
There have already been significant output from CERN. The WWW, for one. Knowledge learned through the development of really big magnets may lead to fusion power sooner. (No, not at LHC. Don't start that rumor.)
Einstein's "why's that" lead directly the A-bomb; and to transistors and solar cells and DVDs; and the LHC.
Hubble's to the big bang; see LHC.
Curie's "huh?" lead to the bomb; and atoms and cancer treatments and cat scans.
Pasteur's "why does wine sour?" to pasteurization and antibiotics. He's also directly responsible for much of the population explosion, but population control through food poisoning and plagues seems, well, you know, natural.
Franklin's "what's lightning?"; he got the sign of the electric charge wrong but the vibrator was one of the first "household appliances" to be electrified.
While it's true that science has obviously led to some very practical things, it's not at all been established that pouring billions of dollar into single facilities will do something like that. It's considered pretty unlikely that the LHC will provide any sort of breakthroughs like the ones you have listed above. (And Einstein's work didn't actually lead directly to the atomic bomb, incidentally. Curie's work is a bit more on the mark in that respect—the atomic bomb emerged out of work in experimental work with radioactivity and particle physics, not the sort of fundamental theorizing Einstein did.) --98.217.8.46 (talk) 00:12, 11 September 2008 (UTC)[reply]
Before that, he pretty much nailed the coffin shut on the "atoms don't exist" thing and his mass-energy equivalence proved pretty handy to Meitner et al. As for predictions, would you please forward tomorrow's FTSE close? :-> Thanks. Saintrain (talk) 16:07, 11 September 2008 (UTC)[reply]
All of you are using one of CERN's inventions, HTML, the internet browser and world wide web. This is a case of scientists working on something not directly related to particle physics, but ending up useful. Graeme Bartlett (talk) 21:20, 10 September 2008 (UTC)[reply]
Somewhat obviously: Specialagent777 why are you posing questions, when as the self-claimed Kwisatz Haderach surely it is us who are supposed to seek your "absolute powers of prescience" and ability to "bridge space and time" - I shall remain severely disappointed in your abilities if you can't answer a simple prediction of what equivalent of "Apollo moon landing effort gave us Teflon non-stick frying pans" we shall get out of the LHC :-) David RubenTalk22:10, 10 September 2008 (UTC)[reply]
Smoking has statistically been related to a high number of complications, primarily dry sockets. Alcohol (as well as hot liquids) will dissolve the blood clot and open the wound to the possibility of infection. -- kainaw™18:07, 10 September 2008 (UTC)[reply]
Not true! One human has already been killed by this device (mentioned in the article)! But as Algebraist said, it was from an equipment/breakage accident, not from Particle Physics Gone Wild. DMacks (talk) 19:47, 10 September 2008 (UTC)[reply]
Well, yes, someone was killed by having a whole bunch of equipment dropped on him. Since no-one's going to be going into the accelerator while it's turned on, this is no longer much of a risk. Algebraist00:12, 11 September 2008 (UTC)[reply]
Yes! One (unlikely) failure mode would be for some part of the machine to explode or start a fire or wildly shoot the proton beam at an innocent bystander. See here for a description of some of the largish energies involved; a full beam could melt a tonne of copper!. That said, there is no chance of it being more dangerous than a good-sized IED. --Sean01:41, 11 September 2008 (UTC)[reply]
(ec) As it says in the lead paragraph of that article, the best-known hadrons are protons and neutrons, which are subatomic particles. The Large Hadron Collider will collide protons. More generally, a hadron is made of several quarks held together by the strong force. Some hadrons are bosons, others (like protons and neutrons) are not. No hadron is a lepton; leptons are something else entirely, and include electrons. Algebraist19:20, 10 September 2008 (UTC)[reply]
Yes, I was tempted to chime in and say it's a dyslexic erection, but that would have been tasteless and juvenile, so I refrained. :) -- JackofOz (talk) 03:11, 11 September 2008 (UTC)[reply]
Does the amount of heat given off by a machine or organism contribute in any way to global warming?
Say we had nothing but solar-powered cars, but their motors cooked away at 200 deg C, or say everyone had a solar powered air conditioner spewing hot air into the streets, would this affect global temperatures in any way?
Thanks!
— Sam 19:28, 10 September 2008 (UTC)
I believe that would violate the first(?) law of thermodynamics. The energy from the sun is already entering our atmosphere (mostly as heat to begin with); harnessing it and converting it will not directly be a problem. It's conceivable that how we go about it can cause some problems, but I don't think this particular worry is well founded. - Lambajan19:43, 10 September 2008 (UTC)[reply]
It's worth noting that there are two different questions here: "does heat given off by <something> affect global warming?" and "does heat from solar-powered sources affect global warming?" I'm inclined to agree with LambaJan on the latter, but the former is not necessarily true -- the fuel source matters. — Lomn21:28, 10 September 2008 (UTC)[reply]
On second thought, I don't agree with the solar-powered thing, either. Solar cells capture light energy that would otherwise scatter away, converting more of it (eventually) to waste heat. — Lomn21:30, 10 September 2008 (UTC)[reply]
It heats up whatever it's absorbed by. Some of it will be reflected back into space, but Earth gives an albedo of 0.367, so only 36.7% of sunlight hitting Earth is reflected back, and I believe most of that is from clouds and oceans, so solar cells on land probably don't make much difference. --Tango (talk) 22:46, 10 September 2008 (UTC)[reply]
(semi-digression) A few jobs ago, we had a bunch of small cartridge heaters that were unlabeled as to wattage. We got pretty close estimates by comparing "how hot does this feel compared to a known-wattage lightbulb?" The net energy coming in eventually becomes heat, regardless of whether it starts "as heat" or "as absorbed light". DMacks (talk) 00:15, 11 September 2008 (UTC)[reply]
Cities are hotter than rural areas (the urban heat island), but this effect is mostly caused by buildings blocking thermal radiation from escaping into the sky. There article's "Relation to global warming" section seems to indicate that the heat island has negligible effect on annual temperatures. --Bowlhover (talk) 00:23, 11 September 2008 (UTC)[reply]
I've actually had similar thoughts. My current stance is that the heat from the sun trapped by greenhouse gases must be more than we produce on earth, but let me share an experience that frightened me: as a special treat, I drove to vegas for my 21st birthday with my brother and a friend. We went during a chilly week and arrived at night, but as we approached the immmediate outskirts of the city, it got SIGNIFICANTLY warmer. I have no doubts the heat of Las Vegas relative to the rest of the dessert is due to energy used by all the casinos, especially the lights on the strip. Electricity use results in heat. Lightbulbs, TV's, computers, cars, hot water heaters....we are surrounded by heat sources, and our electricity consumption might correlate somewhat with the rise in global temperature. Lambajan mentioned the first law of thermal dynamics, but most of our energy is drawn from coal and petroleum: energy from the sun that was stored long ago and is being released long after the fact en masse. Could ground level heat production effect world temperature? It's possible, But I don't know whether it would be significant relative to other sources. --Shaggorama (talk) 03:58, 11 September 2008 (UTC)[reply]
Yes, it has an effect, but no, it is not significant. The solar constant is about 1360 W/m2, or 340 W/m2 if averaged over the surface of the Earth. Even Vegas is much darker than that. The increased temperature you feel is mostly due to stored heat from the day being re-radiated, from decreased cooling due to the more complex artificial landscape, and from decreased air exchange due to buildings. I felt exactly the same effect you describe when entering Kata Tjuta about a months ago, and there are no external heat sources to blame there. --Stephan Schulz (talk) 08:56, 11 September 2008 (UTC)[reply]
With reference to the photovoltaic panels mentioned earlier, you might like to note that they would typically be reflecting more solar radiation back into space than the average albedo of 37% cited earlier. A researcher for a leading PV manufacturer gave me figures a while back of 50% reflected, 15% converted to electricty and 35% kept as heat. This could vary quite a lot though. Efficiency rates are gradually climbing and there are transparent modules available which can be used to replace glazed areas in buildings. If vast PV power stations are to be placed into deserts then the issue would have to be considered. It would probably e better to convert as much of the solar radiation as possible into electricity than to reflect it back into space. But in the solar energy article there is mention of deliberate attempts to increase albedo, simply by painting surfaces white. Itsmejudith (talk) 08:23, 12 September 2008 (UTC)[reply]
All the solar radiation that hits the Earth is radiated back out into space one way or another (some of it gets turned into plant matter, but only a tiny percentage). It is either reflected directly as light waves or radiated as infrared heat. It is the infrared portion currently causing our problems with global warming - increased CO2 and other trapping gases absorb the infrared radiation emitted from the ground, that heat energy has to be re-radiated from the upper atmosphere, and a new equilibrium is established at a somewhat higher overall temperature. The amount of energy absorbed from the Sun by our planet is truly vast though, and it is all heading back out. As far as "vast" PV stations in the desert - think about what vast really means. If you covered even one whole desert for solar power, you have covered very little of the Earth's entire surface, and the area doesn't match natural variations in cloud cover and seasonal snow and ice cover. According to our article, the "usable energy" received from the Sun is 8,000 times 2004 human energy use from all sources. By my figures, we need three spots around the globe, 250 km square, carpeted with 25% efficient solar cells, and we're covered. Franamax (talk) 09:33, 12 September 2008 (UTC)[reply]
No. Blood (and indeed all of you) is mostly water already. Saline injection is standard for treating severe dehydration. Yeah, it's "saline" but only very slightly (not like oceanic salt-water). The main risk for "pure water" would be if huge amounts were injectedf aster than the kidneys (etc) could remove the excess water--then the blood would get diluted and its transport properies would change. DMacks (talk) 19:45, 10 September 2008 (UTC)[reply]
Pure water? Yes - painful. Yes - dangerous. I know of a case where sterile water was infused intravenously by mistake instead of saline. And it was extremely painful. It is also dangerous, because the lowering of the osmolarity of the plasma may lead to hemolysis, and well as damage the endothelium. Large quantities? Lethal. --NorwegianBluetalk20:53, 10 September 2008 (UTC)[reply]
Meaning the lysis of red blood cells exposed to that pure water before/while it was diffusing. So a drop or two no big deal (and even if you lose "only a few" cells, probably wouldn't notice) but a syringe-full would take noticeable time to diffuse and noticeable gradient while doing so I'd assume. DMacks (talk) 00:11, 11 September 2008 (UTC)[reply]
You can give yourself an idea of how much your body prefers salt water by first pouring pure water up your nose, and then pouring salt water. The latter is *much* more comfortable. See neti. --Sean02:27, 11 September 2008 (UTC)[reply]
I'm not trying to be rude in anyway, so please dont take this the wrong way... Why do so many women not have a mind of their own? They'll date a guy or get with a guy that their friends think is good looking. They'll leave a guy they are interested in only because their friends do not like the guy (usually the fat friend that cant get guys). They dont live for themselves, they live for other people. Not all of them, but many of them. Why is this? I don't know any guys that are like this —Preceding unsigned comment added by 75.82.33.31 (talk) 21:44, 10 September 2008 (UTC)[reply]
Independent, intelligent women pay a price in modern US society. Most men will not put up with it and make such clear in their actions if not always their words. As a result the vast majority of women are socialized into being quiet, submissive, non-threatening. I find it pretty disgusting (and damning of this so-called "free" society). My wife is independent and intelligent and has had to put up with a lot of crap from men over the years. --98.217.8.46 (talk) 23:59, 10 September 2008 (UTC)[reply]
The OP is talking about women being submissive to their (presumably female) friends, not to men. If women in the US are quiet, submissive and non-threatening, then I think I should probably move there - the women in the UK are far from it! --Tango (talk) 00:05, 11 September 2008 (UTC)[reply]
Men actually do the same thing, in their own way. In certain male-only social circles, it can be seen as unmanly and disrespectful to put one's wife or girlfriend (especially a recent one) before one's buddies in terms of social contact and free time allocation. It's the whole (to be blunt, 'cause this is what's said) 'Hos come and go but your bredren are forever'/'Bros before hos' thing... --Kurt Shaped Box (talk) 00:19, 11 September 2008 (UTC)[reply]
I've actually noticed the opposite in quite a few women I know or know of. The amount of crap they're prepared to put up with from guys who are obviously dyed-in-the-wool dirtbags who'll never change astounds me sometimes. Occasionally, when all the cheating/excessive drinking/laziness/disappearing for days on end with no explanation/spending her money or pawning her jewellery without asking becomes too much for her, she'll sling him out on his arse - but it seems like nine times out of ten, she'll take him back after a few days, only for nothing to change at all. I don't know of many (any?) men who'd accept that sort of behaviour from their girlfriends or wives. --Kurt Shaped Box (talk) 00:13, 11 September 2008 (UTC)[reply]
I was mostly talking about girls that are 15-25, I know they become more mature and make better decisions as they "grow up."
Social contacts are important to both men and women. Also, if other people find another person attractive for whatever reason, this tends to increase the perceived 'value' of this other person, and it doesn't matter whether we're talking about males or females. There is always a degree of competition involved in these sort of things, and for better or worse, someone is far more likely to persue a person other people find attractive and for that matter, find the other person attractive. Finally, I don't see any reason to presume these people aren't living for themselves. Their friends are obviously going to be important to them... Why should this man, who doesn't get along with their long term friends be more important to them then their long term friends? Of course it could be the friends at fault, but people are apt to take the side of the person they have known for longer and often miss some of the flaws in the people they know well. Besides that, if the man they're dating is talking about or thinking about "the fat friend that cant get guys" I would say it is actually the man who is at fault, and good on the girl for dumping that jerk. It's likely to be not in their interest to date such a jerk. To put it a different way, if the girl is happy with her life and friends, how can you say they are not living for themselves just because they choose to reject those who don't fit in with their existing life? Of course, as life priorities change, the importance of friends may change and also an increasing priority for finding a stable long term partner (as opposed to simply one that looks good to other people) but I don't think it's that simple. The people they are dating also change/mature and perhaps are less likely to think about "the fat friend that cant get guys" and also, the person herself is less likely to even be interested in such a guy in the first place. In other words, both parties are maturing and changing, you can't just put it down to one. P.S. As others have said, most of this holds true in some way for men as well. Most men actually do care a lot about what other people think of other any girl their interested and are far more likely to pursue someone perceived as hot then someone who is not... And a lot of men are not going to be involved for very long with someone who does not get along with their friends (the may perhaps keep the relationship for a bit longer then would most females if they're at least having sex). Perhaps the biggest difference is that I suspect, for a variety of reasons, a man is far more likely to not get along with a woman's friends then a woman is with the man's friends. Nil Einne (talk) 17:20, 11 September 2008 (UTC)[reply]
I don't see a specific name for a telephone with a signaling crank, though the contemporary separate-transmitter-and-receiver design was known as a "candlestick". — Lomn23:28, 10 September 2008 (UTC)[reply]
A search on Google indicates the present term is "hand crank wall telephone." In the days when they were in common use, they were probably just calld a "wall phone." In an 1899 book on telephones "American Telephone Practice" by Miller, a drawing of a wall phone with a crank is just titled "Complete telephone instrument" while the candlestick phone illustration is labelled "Desk telephone set."Edison (talk) 03:24, 11 September 2008 (UTC)[reply]
A a child when I heard on tv cop shows about someone receiving "crank telephone calls," I supposed that they must have been made from one of these old instruments. Edison (talk) 18:43, 11 September 2008 (UTC)[reply]
I'm more inclined to the belief that rather than the instrument, it is the caller being referred to: crank (Old English, cranc) ...an eccentric person...; cranky ...full of whims, cross. Hey, there's even a picture of me in the dictionary! :)Franamax (talk) 09:04, 12 September 2008 (UTC)[reply]
Ok, Wikipedia, here we go. The chemistry class (highschool level) I am aiding for recently did the "Cu wire in silver nitrate solution makes crystals of silver and Cu solution" experiment. The teacher then had an idea to scrape the silver off of the copper wire and melt it somehow. We scraped it off and we have this pile of nitrate soaked silver to work with. We are both wondering whether a methane flame will be enough to get a crucible up to 1234 K or so to melt the stuff. Here's how I'd do it, gathered from some web surfing:
1. Get more silver from the nitrate solution
2. Dry lump of stuff in the crucible first
3. Get it out of the crucible and melt some borax in the crucible (to give the silver a slippery surface to slide around on so that we can pour it out easily? a good idea?)
4.Put the silver back in the (cooled) ceramic crucible, add flux (I read this is good to have to prevent dissolved gas in the melted metal...what is it?) and but the spurs to it.
Anybody have corrections/ improvements on my procedure?72.219.139.201 (talk)
Here's some good ideas! My try will be on a smaller scale than that, but the idea of stoking a flame with the blower helps me out...hmm I don't think it would help a methane flame but maybe some mini-charcoal action is due.72.219.139.201 (talk) 05:01, 11 September 2008 (UTC)[reply]
So I managed to grab one of the buggers. Any ideas? seems pretty flea-like to me. This one was actually a little larger than the rest of them, ~3mm. Sorry for the poor quality, I don't have a good macro lens and I stuck this guy between packaging tape.
Yeah, that's a cat flea. Nasty things. Check with the vet about giving a kitten the anti-flea stuff, but if he or she is cool with it, really, the Advantage/Frontline stuff is super easy (you put a little squirt of it behind their neck and pow! no fleas for a month). --98.217.8.46 (talk) 00:01, 11 September 2008 (UTC)[reply]
salt grain physics.
When I was a child , I wondered what would happen If a grain of salt had all of its atoms pushed together so that they all touched.
Under extreme pressure the molecular bonds such as those in a salt crystal breaks. The bonds between electrons and the nucleus in atoms may also break and you may get matter similar to what a Neutron Star is composed of. It may become a superfluid but we're not really sure because we can't create these immense pressures in a lab. EverGreg (talk) 09:29, 11 September 2008 (UTC)[reply]
Tangentially, this reminds me of something Sir James Jeans said: "Put three grains of sand inside a vast cathedral, and the cathedral will be more closely packed with sand than space is with stars." --- OtherDave (talk) 15:46, 11 September 2008 (UTC)[reply]
Are you sure about that? The back of the envelope calculations I just did show the cathedral would need to be several square kilometres in size to have the same density as the central parsec of our galaxy. --Tango (talk) 18:28, 11 September 2008 (UTC)[reply]
So assuming we only have the mass of a salt grain and we pushed the nuclei together [somehow :) ] (overcoming the strong force) would we get a mini black hole or would it flash out as an energy burst ...what would happen? —Preceding unsigned comment added by 84.13.83.29 (talk) 19:45, 11 September 2008 (UTC)[reply]
If you overcome the force holding the electrons apart, you get something similar to a neutron star. If you carry on and force the nuclei together it will eventually collapse into a black hole which would very rapidly evaporate via hawking radiation. --Tango (talk) 22:31, 11 September 2008 (UTC)[reply]
Just something that came up in conversation with a friend today. Why is it that a tame female parrot might be perfectly happy to trust you with her life and safety as her owner/companion, yet completely refuse to trust you when it comes to the safety of her eggs and chicks? Yes, even tame hens generally hate it when you go near their nests (say to count eggs or periodically check on the wellbeing of the young) and go into full-on 'angry protective mom' mode... --Kurt Shaped Box (talk) 00:33, 11 September 2008 (UTC)[reply]
This is not confined to parrots. There are many instances of birds developing an extra protective attitude when nesting. Blackbirds, normally timid, can be very aggressive towards anyone who comes too close to their nest, especially when they have nestlings. And swans, while docile and amenable for the rest of the year, can turn into mean critters in the nesting season. Lapwings (green plover, peewit)develop distractive behaviour during nesting to lure away potential predators of its eggs or young. The latter behaviour, while not aggressive, indicates the ability of some birds to alter their behaviour according to the circumstances. This is presumably an instinctive behaviour to protect its progeny. 86.4.187.55 (talk) 06:20, 11 September 2008 (UTC)[reply]
A completely different hypothesis is that they are pretending when you think they trust you. And most of the time, you're anthropomorphizing, anyway, meaning that behaviour in presence of humans all is learned in order to get at food etc. --Ayacop (talk) 07:36, 11 September 2008 (UTC)[reply]
I think anthropomorphism is definitely a big part of the picture. These are birds, not humans, and they aren't very smart. They don't think, "oh, hey, that nice guy feeds me and pets me, so I can trust him with my eggs", because they aren't really thinking in logical chains like that. I mean, parrots are pretty smart birds, but they're only smart by bird standards -- that doesn't mean they're capable of abstract thought. -- Captain Disdain (talk) 08:35, 11 September 2008 (UTC)[reply]
I don't really think that it's anthropomorphizing too much to suggest that a psittacine which remains totally calm and placid when picked up by its owner and cuddled, or rolls over and allows its belly to be scratched, or willingly places its head inside a human mouth to pick food from its owner's teeth (note: don't do this - our mouth bacteria can make birds very ill), or chooses to sleep snuggled up against its owner's head at night 'trusts' (and perhaps even 'likes') that one certain human. Are they smart enough birds to fake all that for the sake of food? --Kurt Shaped Box (talk) 17:31, 11 September 2008 (UTC)[reply]
I'm not saying that they're faking it. That's kind of the point, actually! They just aren't smart enough to make the logical connection that would allow their trust for you to overcome the instinct that tells them to protect their eggs, even though they have genuine affection for you. That kind of thing would require pretty advanced capacity for abstract thought, and they don't have it -- either that, or pretty serious conditioning. -- Captain Disdain (talk) 22:43, 11 September 2008 (UTC)[reply]
I don't think it's confined to birds either. Many mammals are far more wary of others including humans when they are taking care of their young. Nil Einne (talk) 17:00, 11 September 2008 (UTC)[reply]
We (my friend and I) were discussing the differences in behaviour between pet parrots and pet cats/dogs, which don't really seem to mind when familiar humans interact with their young - even when they pick them up and play with them. On the other hand, something like a pet cockatoo or cockatiel (my friend has some) would go *absolutely fucking ballistic* if you tried the same thing with its chicks. --Kurt Shaped Box (talk) 17:31, 11 September 2008 (UTC)[reply]
I don't think that is entirely true. Many mother cats and dogs will be concerned if you try to handle their kittens/puppies particularly when they are very young. They may either react against you (snarl/hiss/try to bite/scratch) or may move them around to try and get away from you (or in extreme cases, may reject the young). Birds may perhaps be more protective then cats/dogs, but I definitely think all are quite protective of their young. (The obvious question is, how many mother cats/dogs and birds have you interacted with? In my case, none at all really but from what I've read I do think it's the case) It's worth bearing in mind that cats & dogs have both been domesticated for a while now whereas most birds haven't really been domesticated as far as I know so comparing the two isn't perhaps a fair comparison. From what I've seen in shows, you have to be very careful for example, with tigers when they've just given birth, even if you regularly handle the tiger normally. Also, I suspect it will have a fair bit to do with whether the animals in the wild are social animals. If it's normal for their young to interact with others at a fairly young age (as I presume it is for wolves) then they're less likely to have a problem with it. This is not the case for most birds (or tigers) so they're more likely to have a problem with it. P.S. What do chickens do? Nil Einne (talk) 18:09, 11 September 2008 (UTC)[reply]
In my experience, chickens just try to run off and lead the rest of their chicks away from you. They work on more of a numbers approach, rather than defend every single chick. Ducks on the other hand can be a little more aggressive. Franamax (talk) 08:48, 12 September 2008 (UTC)[reply]
Cat Induced Allergies
About 2 and a half months ago we got a 5 year old white Persian cat. It has no ticks and flea infestation and we bathe it regularly about every week or 2 weeks as needed. Basically it is a healthy cat.
Recently about a week ago my Dad started complaining about allergy to the cat. But I believe that he is overacting. He is complaining of flu and throat complications. And I am of the opinion that this could very easily be due to viral or bacterial infection.
My younger brother has allergic problems but throughout the 2 months stay of the cat he had no allergic reactions but about a week ago when his college opened he started having nose irritation etc. And that of course is because he now regularly breathes polluted (smoke, dust etc) air when traveling in the bus, at least that is what I believe.
On the basis of the above my Dad is insisting that we part with the cat. I am of course opposed to the idea. I have read somewhere that living with a pet cat can actually make your immune system resistant to cat allergies. Therefore I am of the view that the cat should stay.
I am not asking for medical advise but rather I would like to know if any of you have undergone a similar experience and the decisions that you made. Because a majority of people have pets or had them at some point in life. —Preceding unsigned comment added by 203.81.205.162 (talk) 00:50, 11 September 2008 (UTC)[reply]
You're trying to make a decision without data. An allergist would be able to perform a test that would tell whether your father is actually allergic to the cat, or not. It's unreasonable of him to insist you get rid of a pet if he doesn't take the test, just as it would be unreasonable of you to insist on keeping the pet if the test determines he's actually allergic. - Nunh-huh04:25, 11 September 2008 (UTC)[reply]
An allergist could also explain more exactly the factor that triggers reaction in sensitive people. Mostly it's taken to the be fur, but there's a range of comment/information on Google about the effect of cat spit on the fur from grooming[20] among other things. Julia Rossi (talk) 07:57, 11 September 2008 (UTC)[reply]
Actually as far as I'm aware it's predominantly due to a? protein in the saliva which get onto the fur from the cat licking (and perhaps other means). This seems to be supported by Cat allergy. Nil Einne (talk) 16:57, 11 September 2008 (UTC)[reply]
Yeah, have them see an allergist to figure out for sure what is ailing them. But you should probably work out the terms ahead of time—if it turns out they aren't allergic to cats, keep the cat, but if they are, consider finding it another home. Don't give it to a shelter unless you are fine with the fact that it will probably be put to sleep. --98.217.8.46 (talk) 01:24, 12 September 2008 (UTC)[reply]
I used to believe that cat shelters meant that until I found out otherwise, and further OR is that while I had cats with short hair, it didn't affect the household, but a persian did with its excessive moltability. The cat had such a nice personality I got it a job in a pet store as the cusstomer service kitty, along with the tame parakeet etc. All true and a great itch relief for the rest, Julia Rossi (talk) 08:32, 12 September 2008 (UTC)[reply]
That's true, I found a Siamese to be the only breed of cat I could tolerate in a house. I like cats (and they like me) but a cat allergy is truly miserable. There is another way for all concerned to get along - get rid of the carpets, vacuum the floors and furniture every day, brush the cat every day and wash it regularly (nyuk - just try washing a cat), dust the shelves and tables every three days, and make sure Dad has an area where the cat is never allowed to go (den and bedroom, for instance). If you really want to, it can be done. Franamax (talk) 11:36, 12 September 2008 (UTC)[reply]
What is a Computer Scientist?
My 10yr. son has to do research so a Computer Scientist. I really need some basic information so I can help him. What's involved in this person job? what type of equipment does this person need? Does this person need a uniform to do his/her job?
Start with our article about computer science. It's a pretty diverse field, ranging from engineering to electronics to programming. One might sit at a desk, work in a clean room, etc. Depending on what one does, one might wear a suit, jeans, a uniform, some sort of safety gear or protective covering over "whatever" you want... DMacks (talk) 01:02, 11 September 2008 (UTC)[reply]
Some say that Edsger W. Dijkstra said "Computer Science is no more about computers than astronomy is about telescopes," giving a clue that computer scientists have been around longer than computers have. Computer scientists were around in the 1800s, as Ada Lovelace was the first computer programmer. --Kjoonlee01:34, 11 September 2008 (UTC)[reply]
He might try focusing on a small number of real computer scientists as an example. Donald Knuth comes to mind. Or Dijkstra. Or possibly compare a naive solution to a problem to a more advanced solution developed by computer scientists. (The obvious Bubble sort verses the unintuitive Quicksort for example) APL (talk) 18:17, 11 September 2008 (UTC)[reply]
In an article in the London Times today, Matthew Parris complains of an incident when he drove up to a petrol pump on the wrong side. As he pulled the hose over the car's roof and attempted to fill up the tank that way, a loudspeaker voice bellowed at him that this was not allowed, and to drive to the other side or she would not switch on the pump.
As flammable liquids are involved I'm tempted to give the cashier the benefit of the doubt. Is there, in fact, any danger in pulling the hose of a petrol pump over the roof of your car and filling up from the wrong side? 81.171.134.226 (talk) 12:01, 11 September 2008 (UTC)[reply]
Sounds like a classic jobsworth. At the worst it'd be a little bit extra wear and tear on the car. People do this all the time (at least in my experience) without concern, and i'm pretty certain if there were any meaningful additional danger that the petrol-station would have clear signs about it (after all the relative danger of being on your mobile phone in a petrol station is small but they still - for now - forbid it.) 194.221.133.226 (talk) 14:08, 11 September 2008 (UTC)[reply]
There's no danger to the pump - it is designed to pump wherever the hose is pulled to. There is possible danger to the customer being on the side of the car that traffic drives past as opposed to being between the pump and the car. In all reality, it is most likely a dumb rule that was made after someone sued the station (or company) for scratches on his or her car. -- kainaw™14:19, 11 September 2008 (UTC)[reply]
I'm told the smart thing to do is look at the little fuel pump symbol on the dashboard before you get out of the car - many indicate which side the filler cap is. Bazza (talk) 14:41, 11 September 2008 (UTC)[reply]
That's not what Bazza means. Many pump symbols include an explicit arrow pointing left or right (my MINI does, and so do most rental cars I rent). Here's an example on a Toyota (quickest one I could find). -- Coneslayer (talk) 15:07, 11 September 2008 (UTC)[reply]
I didn't mean an arrow, I did mean the side the pipe is positioned, as described in the Snopes article. The car I drive (VW) does what I said and, from 81's comment above, so do others. Different makes may not. Both Snopes and I, therefore, can be considered correct, especially if I pedanticly change "many" to "some" in my note above. Bazza (talk) 15:46, 11 September 2008 (UTC)[reply]
Just go back in time maybe 25 years or so, when many cars had the fill-pipe centered in on the rear. The license plate, which was on the fixed frame not on the trunk-lid, was the cover. DMacks (talk) 15:56, 11 September 2008 (UTC)[reply]
Not in Britain they didn't! I had a "solve it yourself" mystery book when I was a boy. The vital clue in one of the stories was to do with Fords having the filler cap under the number plate - now we had a Cortina, and I knew damn well that the filler cap was on the side. Being unable to solve the mystery because the publishers had failed to adapt the book properly to the British market was a great disappointment to me. DuncanHill (talk) 16:00, 11 September 2008 (UTC)[reply]
I don't think there will be any danger but it sounds to me there might be some reasons why they won't want you doing it. Firstly if the hose isn't far enough to reach the tank, the person may try to stretch it to reach. This is unlikely to be dangerous but may increase wear and tear on the hose. Secondly if the person is extremely lazy, they may not bother to put the hose back properly and may just leave it lying across the road. Again I doubt there will be any danger but it may be ran over (again increasing wear and tear) and/or requires the attendant to go and put it back. Thirdly if someone knocks the hose it may be damaged and of course is likely to damage the car that hits it (again probably not dangerous but may liable to make problems for the petrol station). Nil Einne (talk) 16:49, 11 September 2008 (UTC)[reply]
Take a look at that picture of the gas pump up above. The hose is partly filled with gasoline from the last person who filled their car up. If you're trying to stretch the hose over to the other side of your car and you lift it the wrong way, isn't there a fairly good chance you'll spill gas all over your car (and yourself)? Franamax (talk) 08:41, 12 September 2008 (UTC)[reply]
Nahh, the shutoff valve in the handle is supposed to prevent that. There's possibly a small amount in the last 8 inches of nozzle, but only if the last person pulled it out REALLY quickly after refueling. --DaHorsesMouth (talk) 22:39, 12 September 2008 (UTC)[reply]
The temperature of intergalactic space is 2.73 K. The operating temperature of the LHC is 1.9 K, and its volume is around 80000 cubic metres. Is there any known region of the universe of this size that is colder than the collider? --Taejo|대조13:20, 11 September 2008 (UTC)[reply]
Algebraist intelligently included "known to astronomers" because it is impossible to know the "coldest" or "hottest" or "largest" or "smallest" anything when referring to space. Most of it is unknown, so we can only answer with "coldest place in known space". And yes, astronomers know about the LHC. It is important to know about something that is guaranteed to suck up Earth in a black hole by this time next year. -- kainaw™14:16, 11 September 2008 (UTC)[reply]
Well, there are labs where they've got down to billionths of a degree above absolute zero, if memory serves. The Boomerang Nebula is the coldest known place that wasn't cooled down by man. --Tango (talk) 14:23, 11 September 2008 (UTC)[reply]
Our article Philippines should contain the information you are looking for. By the way, this sort of question is probably better suited to the Humanities desk. Oh, and try not to use ALL CAPITALS when asking questions - it can look like you are shouting and may annoy some users. DuncanHill (talk) 13:58, 11 September 2008 (UTC)[reply]
Welding under water
What are the processes taken to weld under water?
Discuss the differences between welding on surface and under water?
What is the trick behind under water welding?
What are the equipments used?
Are the equipments the same as surface welding?
What are the side effects on welder?
Which is stronger surface or under water welding?
What is the meaning on the abbreviation written on surface electrode?
Does the carbon light has effect on eyes as in under water welding?
What are the conditions for a surface welder to become an under water welder?
Lastly
Every other things describe under water welding
As noted prior to that parenthetical expression, it's because physics models generally treat time in that fashion. In a closed system, entropy increases (per the second law of thermodynamics). This is a convenient shorthand for time with regard to otherwise time-symmetric equations. The statement should not be interpreted in isolation, however -- it is not an attempt to say that you and I examine the entropy around us to determine that time exists in the everyday. — Lomn15:21, 11 September 2008 (UTC)[reply]
It's interesting to note that the 2nd law of thermodynamics, or at least the logic behind it, is time symmetric. Entropy ought to increase in both directions in time from any given point (which isn't actually possible, of course, so I guess it would all just cancel out and stay roughly constant), it's just because the big bang had extremely low entropy, so entropy in the past is fixed at a low point, that it can only increase towards the future. --Tango (talk) 17:20, 11 September 2008 (UTC)[reply]
Try this thought experiment. Suppose you and the whole universe suddenly start to move "backwards in time", all physical processes are exactly reversed, and your memories are erased as you go back. So when you get "back" to one hour ago you have exactly the same memories as you had the first time you went through the time-point "one hour ago", the only difference is that you (and the universe) are now moving in the opposite direction along the "time dimension". How would you know that time had reversed ? How could you tell ? Does this concept of "moving backwards in time" even make sense ? In The End of Time Julian Barbour argues in this way that time is an illusion, and that the only reason we peceive time as flowing in the direction of increasing entropy is that this is the only way in which memory can work, given the second law of thermodynamics. It is impossible to remember the future, not because "it hasn't happened yet", but because it is a state of higher entropy than the memory itself. Gandalf61 (talk) 15:25, 11 September 2008 (UTC)[reply]
Shouldn't the psychological arrow of time be pointed in the opposite direction? Being as objective as I possibly can, I'd like to state that my thoughts are far more ordered now than they were when I was 13. Sappysap (talk) 23:36, 11 September 2008 (UTC)[reply]
Indeed - it's not a closed system, and that's the key detail. In order to store a memory you need to use energy and that's going to increase entropy somewhere (heating the air around you, turning food into carbon dioxide and water, etc). --Tango (talk) 21:27, 12 September 2008 (UTC)[reply]
In Wikipedia's article on needleguns, there is a section heading entitled "Advantages" which gives a whole bunch of advantages of needleguns. There is no section heading called "Disadvantages", and no discussion of disadvantages in the article. Yet, clearly, there must be significant disadvantages, because if there weren't, then everybody who uses guns would be using needleguns — while in reality, the opposite is true: needleguns are extremely rare in comparison to other types of firearms. So, what are the disadvantages of needleguns, and could someone please add them to the article? —Lowellian (reply) 16:21, 11 September 2008 (UTC)[reply]
I've heard of flechettes, but didn't know people used the term "needlegun" to refer to such things. I'd assumed "needleguns" were sci-fi only. High-velocity, high sectional density projectiles would tend to overpenetrate, which is a disadvantage. But, this is just me speculating, and I'm not a reliable source, so I don't think I'd want to stick this into the article. Friday(talk)16:35, 11 September 2008 (UTC)[reply]
Well, I would guess the major disadvantage is that they are mostly hypothetical. I'm not aware of an existing system. Talking about handguns, hypothetically of course, the major disadvantage would be the low stopping power. Needles penetrate well, but do little damage. The overall energy of the projectiles would also be rather low, implying low range. Also, it's unclear of how to power such a gun. Chemical with a sabot would eliminate most advantages (rate of fire, ammunition size) while adding complexity and inaccuracy (the sabot needs to be accelerated and drops away in flight). For more Sci-Fi approaches, you would need a portable power plant, which might not be reasonable. --Stephan Schulz (talk) 16:42, 11 September 2008 (UTC)[reply]
A "needle" gun actually doesn't make a very effective weapon, as the small mass of a needle slows down much more rapidly in flight than a bullet and hence has limited range and accuracy. Most flechettes actually look more like nails than needles, and that's largely to provide them enough mass to be practical. Dragons flight (talk) 21:03, 11 September 2008 (UTC)[reply]
Was there German Genetic Engineering using X-rays in 1945?
After World War II, in the years 1945 to 1947 the U.S. took besides many factories all intellectual property that they could from Germany, all patents, the industrial processes etc. (good book on the topic)
A U.S. agricultural officer (colonel) in occupied Germany wrote a book about his experiences in occupied Germany, it is available online. This is a quote about one of the things they took in 1945.
"Members of our agricultural staff were in time to discover some rather interesting and intriguing developments in plant science, especially about the production of higher-yielding plants by breaking up certain chromosomes through radiation. Some of this got to the United States and is widely applied in areas of grain production and horticultural research today."[21]
Is he speaking about a form of Genetic Engineering by inducing mutation using x-rays, or is it be something more advanced?
What is this method/technology that the Americans copied from the Germans called?
The use of a large variety of mutagens [22] to help generate varieties is extremely common place in modern day plant breeding (check the article) and has been since around the end of WW2. Take a look at this image for example [23]. No, it's not usually considered genetic engineering. However it is rather different from what many people seem to have in their minds (particularly those nuts about organic farming who hate anything involving GE) about someone breeding different varieties they find until they get a plant they want. Nil Einne (talk) 17:50, 11 September 2008 (UTC)[reply]
The systematic use of radiation to induce mutation was done far earlier than World War II. Thomas Hunt Morgan was experimenting with radiation as a way of producing different varieties of fruit fly as early as the 1910s. I don't know precisely who started using it for specifically agricultural purposes but the fact that mutations in large populations could be increased with radiation doses had been figured out pretty early on, and I would not be surprised if it was one of the many approaches taken at agricultural stations in the US pre-WWII, but that's just my own speculation. It's not necessarily the best way to get new varieties, though. --98.217.8.46 (talk) 23:28, 11 September 2008 (UTC)[reply]
Over my head
I have a teacher who has a habit of looking over everyone's head while he's teaching class. He looks somewhere above the windows in the back of the room. I used to know a guy that did this whenever he was talking to someone. He'd never look you in the eye while talking. Is there a term for this? Dismas|(talk)17:44, 11 September 2008 (UTC)[reply]
I don't think there's a term for it, since it could be any of several unrelated reasons someone may appear to do this. Two social issues come to mind are nervousness (feeling awkward making eye contact) and some sort of aloofness/snootiness (looking down at someone while talking). OTOH, could be a vision problem: a co-worker years ago always looked like he was looking a few feet to the left of where he actually was looking, which if you didn't know it, you'd always think he was ignoring you and listening/talking to the person two chairs over. DMacks (talk) 17:58, 11 September 2008 (UTC)[reply]
I typically don't make eye contact when I talk (and teach as a TA). It's something I'm working on, but never felt like doing. For me, I believe it's because I'm a strong auditory learner - I'm not actually "looking" at or even "focusing" on anything, I'm just devoting more of my brain to hearing than seeing and more or less "shutting down" my eyes for a bit. I don't really need to look at faces/body language - I get almost all of my cues from the tone, inflection, etc of voices. I know it's distracting to some people, but it's who I am. If you force me to look at you, I'll probably forget what you said. Actually, that might even be some very mild autism, but I've never been tested. (I know that didn't actually answer your question for a term, just something I'd like people to know :) --Bennybp (talk) 19:12, 11 September 2008 (UTC)[reply]
I always avoid eye contact. Not out of rudeness, but due to poor vision, as mentioned by user:DMacks. Because of my vision I find facial expressions hard to interpret, so avoiding eye contact allows people to know that I don't register their expressions. Fribbler (talk) 22:49, 11 September 2008 (UTC)[reply]
How come there are so few transitional fossils? Also note that in many cases when pro-evolutionists say "we know the answer to that" it often means that they have come up with a suggestion which they think is plausible - not that they have found evidence that it happened that way. DJ Clayworth (talk) 20:38, 11 September 2008 (UTC)[reply]
Actually, there are quite a lot of transitional fossils. I remember scaring off a Jehovah's Witness when I was a university student by offering to show him some of my palæontology textbooks, after he had made a similar "point". DuncanHill (talk) 20:44, 11 September 2008 (UTC)[reply]
Claiming lack of evidence for evolution is evidence against it is just as wrong as claiming that lack of evidence against it is evidence for it. It doesn't matter if anyone has clear proof of transitional fossils or if anyone can show clear proof of anything. Evidence against evolution must be real evidence, not a claim about lack of evidence. -- kainaw™23:46, 11 September 2008 (UTC)[reply]
That's not entirely true - if you can show that a theory would produce a certain type of evidence with a high probability and you can't find that evidence, that would suggest the theory is false. For example, I theorise that no humans can fly since if any could fly I would almost certainly have heard about it. --Tango (talk) 23:52, 11 September 2008 (UTC)[reply]
A failed test of a hypothesis is evidence against the hypothesis. That is evidence. Claiming that a hypothesis has not been tested is evidence against the hypothesis is not evidence against the hypothesis. On this specific topic, there are claims such as "Evolutionists cannot show me a half-monkey/half-human, so that means there is no such thing as evolution." There is no hypothesis in evolution that there exists half-monkey/half-humans. So, the lack of proof that there are half-monkey/half-humans is not evidence against evolution. Similarly, evolution doesn't claim that each and every fossil will survive through all time and be found. So, lack of evidence of fossils is not evidence against evolution. I have a problem with both sides of this argument. Evolutionist for evolutionst sake do not have a clue what they are talking about. Anti-evolutionists (all lumped together) for anti-evolutionist sake do not have a clue what they are talking about. -- kainaw™00:00, 12 September 2008 (UTC)[reply]
Ah, now you're describing the straw man fallacy. However, I disagree with the statement "There is no hypothesis in evolution that there exists half-monkey/half-humans.", given a sufficiently incorrect definition of "monkey" (you have to interpret words in the way the people saying them mean, rather than what they actually mean) there should be some creature inbetween "monkeys" (proto-hominids, I think would be a more accurate term) and humans. Scientists looking for such a link and not finding on is evidence against evolution (it's not very strong evidence, though, given the fact that most creatures don't end up fossilised so you have to get pretty lucky to find one and there are plenty of places we still haven't looked). --Tango (talk) 17:55, 12 September 2008 (UTC)[reply]
One thing that's always bugged me, not necessarily about evolution per se but our understandings of it, is why humans are so vastly overpowered in terms of cognitive ability compared to other primates. I mean, a human being that was half as intelligence as our species potential maximum is still capable of surviving just fine even in a hostile environment. (I suspect the answer has to do with the fact that there were multiple smart-primate species competing with one another, because if it is just humans against other animals, I doubt we'd have gotten this smart, but humans against other smart things, well, then you've got an arms race.) I've never really seen this fleshed out well, in part because our understanding of the nuts and bolts of human evolution is pretty speculative (a fossil here, a grave there). --98.217.8.46 (talk) 23:20, 11 September 2008 (UTC)[reply]
Are you familiar with Neanderthals? Exactly how they ended up extinct and we ended up thriving is still an open question, as far as I know (although I remember reading recently about some evidence that they were just as intelligent as early Homo Sapiens). --Tango (talk) 23:24, 11 September 2008 (UTC)[reply]
Of course I'm familiar with Neanderthals, but it doesn't really solve it for me. The existence of one other somewhat intelligent primate species doesn't really explain why we're so overpowered. This isn't an anti-evolutionary complaint, just a "boy we really don't understand this" complaint. My deeper suspicion is that the human propensity for intra-species violence—far more than most other animals—is somewhat related to this. (Of course Darwin thought it was probably sexual selection, which is fairly similar.) But it'd be nice to have a better understanding, or at least a better model, of how you get to such a point. --98.217.8.46 (talk) 12:47, 12 September 2008 (UTC)[reply]
You're absolutely right, I didn't mean to suggest Neanderthals would give you the answer, just that they're an interesting topic closely related to that question. It's still an open question, as far as I know. --Tango (talk) 17:48, 12 September 2008 (UTC)[reply]
Intelligence is not, prima facie, a superior evolutionary trait - and this is something that a lot of people who argue about evolution get hung up on. From an intelligent level, we can look and say, hey, great - with science we can increase fertility, defeat the elements, and hunt to extinction anything vaguely resembling a predator, sure. But that's the conclusion begging the premise. I think a useful read is called "The Sickness Gene" or something along those lines - the trifecta of surviving to breed, breeding "most", and having offspring that hit A+B is all there is. In that respect, humans are a vastly inferior form of life to bacteria and cockroaches (and, from a health perspective, a viral epidemic could effectively obliterate the human population... extremophiles would require an astronomical event to be substantively impacted). I believe Mike Judge's movie Idiocracy was another illustration of the principle of evolution - the most fit to breed is not the qualifier we tend to think it is. Sorry, but there's really no counter-evolutionary evidence - Darwin's finches and micro-evolution are difficult to argue with. The best that can be done is circumstantial arguments - OH, HA HA, it turns out that the velociraptor didn't, actually, evolve into turkeys, take that Science! All your precious THEORIES are now rebuffed! ... no, sorry, it doesn't work that way. No more then forgetting to carry a one, one time when you're doing times tables means you're a fundamental failure when it comes to multiplication. 98.169.163.20 (talk) 00:08, 12 September 2008 (UTC)[reply]
By plastic, you probably mean ceramic since plastics that we experience in everyday use could not sustain the acceleration of being fired from a gun. As far as ceramics, there are some that could easily withstand being fired from a gun better than lead/metal, but they cost much more than lead/metal used in bullets. Since bullets are good enough as is, there is no need to spend more. -- kainaw™18:58, 11 September 2008 (UTC)[reply]
(edit conflict) I think Mr. K. actually means rubber. Rubber bullets and other types of nonlethal munitions are more range specific. Depending on the charge, rubber can be lethal or so harmless as to be ineffective. They sell them for different ranges but changing bullets on the spot is impractical for a last resort weapon. That's why they're mostly used for crowd control, when they can plan better on how to respond. There are arms manufacturers working on nonlethal guns where you can 'dial in' your range for rubber munitions (air power), but those aren't widespread yet. - Lambajan19:14, 11 September 2008 (UTC)[reply]
And just so Mr K understands, plastic bullets (or rubber bullets) are not simply a different kind of bullet fired from a normal gun - they are large projectiles fired from a special kind of gun: which explains why cops don't use them in their handguns. DJ Clayworth (talk) 20:35, 11 September 2008 (UTC)[reply]
Agreed. It's sometime after the end of the inflationary epoch, which ended at about 10-32 seconds, but before the weak force separated from the electromagnetic force at about 10-12 seconds. For a ballpark figure, I think this was the typical energy per particle at about 10-13 or 10-14 seconds after the Big Bang. Gandalf61 (talk) 12:50, 12 September 2008 (UTC)[reply]
I was never happy with the inflationary epoch. "We don't see magnetic monopole, so maybe they are far away!" There was no attempt to apply the scientific method. Although now that I read Alan Guth's article it sounds as if WMAP confirmed some predictions of his theory? The article is vague and unsourced - can someone expand on that for me? PlasticupT/C16:12, 12 September 2008 (UTC)[reply]
It is very common for Architects/Civil Engineers to propose designs for currently unconstructable buildings. Like Frank Lloyd Wright's The Illinois. It is a "portfolio" piece, that is it won't be built but shows the designers abilities. Fribbler (talk) 22:57, 11 September 2008 (UTC)[reply]
I would think a key component of a designer's ability is their ability to design something within set limits - "possible to build" would be a limit I would set on any commission for design work. --Tango (talk) 23:21, 11 September 2008 (UTC)[reply]
The same company was pitching this idea in Tokyo until there wasn't enough money there for it. Now, they are pitching it in Dubai - until that money dries up. My opinion - they increase their stock revenue by pitching these ideas and profit. Then, they invest elsewhere until they find a new area to pitch an idea to. They buy back their depleted stock, pitch the idea, drive up their stock value, and sell. -- kainaw™00:04, 12 September 2008 (UTC)[reply]
This is approaching the idea for a mini-arcology. It's not really practically feasible with the technology and costs of that technology that we have today. Also, attempting to insure this building would be a nightmare. —Lowellian (reply) 05:11, 12 September 2008 (UTC)[reply]
When an engineer scrutinizes the plans and tells me it's not possible then I'll believe it's not possible. If Kainaw's right and they're going around pitching this thing and the only problem is not enough money then it probably is possible. I'm sure that if Japan turned it down because their engineers gave it a 'thumbs down' then they wouldn't be able to pitch it anywhere else. - Lambajan13:40, 12 September 2008 (UTC)[reply]
It was never given a thumbs up in Japan. The only reason anyone really heard about it was because it was featured on a Discovery program about really big buildings and some other channel that had a show about really big things. The shows made every attempt to give the appearance that this building was going to built soon in Japan, but the truth is that there are no current plans to build. It is just a small group of guys pitching the idea here and there. I figure that when this idea runs out, they'll start pitching either cities in orbit or under-ocean cities. -- kainaw™14:05, 12 September 2008 (UTC)[reply]
September 12
If the LHC created a black hole...
Or more generally, if a black hole were to appear on or near Earth's surface(presumably a small one, but let's say it's just big enough to avoid collapsing into Hawking radiation), how long would it take to swallow up the entire planet? And what would happen to the rest of the solar system? 68.123.238.140 (talk) 02:10, 12 September 2008 (UTC)[reply]
Longer than the expected life of the solar system, and no effect. Even if it swallowed the Earth in a day, the solar system would be fine -- you'd still have an Earth-ish mass orbiting the sun. — Lomn02:25, 12 September 2008 (UTC)[reply]
Another related question: how big would a black hole need to be in order for there to be exactly 24 hours before the earth was gone? Nadando (talk) 04:07, 12 September 2008 (UTC)[reply]
Cannot be computed exactly. In fact, a silly question (do you need a 24h message in advance?). Next black hole question, please. --Ayacop (talk) 08:00, 12 September 2008 (UTC)[reply]
It's amazing how ill-informed scientific reports, scare stories and other paper selling drivell is generating an unprecedented interest into an amazing scientific work that might have gone unnoticed outside of the ususal aficionados. 190.244.186.234 (talk) 11:47, 12 September 2008 (UTC)[reply]
Rather a high level of WP:BITE here: please avoid pejoritives such as "silly," "drivell (sic)," and "irrational" in responses. Lomn has the right idea in providing a reasoned and informative response without insulting the questioner. Edison (talk) 19:01, 12 September 2008 (UTC)[reply]
Have any scientists calculated the beam energy scale where we would actually say "Hmm, maybe we better not try that"? Could it be the next machine after the SHLC? Franamax (talk) 19:27, 12 September 2008 (UTC)[reply]
I don't know how higher energies are likely to cause problems, regardless of how high they get (assuming the equipment is built to handle that much energy - obviously if the machine explodes that would be undesirable! It wouldn't destroy the planet though, just Switzerland. ;) ). All the fear with black holes is nonsense, it doesn't matter how much energy is involved, black holes just don't behave in ways that would swallow the Earth like that. --Tango (talk) 21:22, 12 September 2008 (UTC)[reply]
Yes, I'm not that interested in the MBH hypothesis, for one thing, we now have an experiment underway to test it :)
However, to take a ridiculous example, if you collided two particles with the same energy as the Big Bang, you would end up with a new expanding universe in your lab, which could have undesirable results. Somewhere between there and here must be a line where problems could result.
Wouldn't there be an energy where you made a black hole big enough that it would be a problem? Or a sufficiently energetic strangelet or powerful magnetic monopole that they would do whatever bad things they might do?
We hear about the harsh conditions on Mars, and how unlikely it is to find life. But Water bears (Tardigrades) have been shown to survive (for 10 days)[24] conditions far harsher than those seen by recent Mars probes, including the vacuum of outer space, temperature extremes, and intense UV radiation.. They can survive ten years without water, temperatures from about absolute zero to 151 Celsius, and 1,000 times the radiation which would kill humans. Could terran Tardigrades survive and reproduce in the Martian polar areas, given that there seems to be liquid water sometimes? (after 6 "database locked" error messages)Edison (talk) 05:16, 12 September 2008 (UTC)[reply]
I don't think there's ever liquid water on Mars (currently, that is), the most it does is sublimate. Also, according to this Wired article: "Tardigrades may even provide insights into adaptations necessary for survival in off-Earth colonies, though they could not live actively in the extreme and nutrient-poor environments of Mars or the moon." -- MacAddct 1984(talk • contribs)05:44, 12 September 2008 (UTC)[reply]
See Extremophile. Even the limited spectrum of life seen on this planet shows that there is probably no environment too harsh for life to develop. There is a very real chance that space itself is liberally populated by micro-organisms which could very well seed planets, satellites, asteroids and comets with the first steps on the way to macro-organisms - I deliberately avoid use of the word "higher" or "more advanced", as being very subjective. 196.2.124.253 (talk) 06:47, 12 September 2008 (UTC)[reply]
The bacteria that can survive in space usually do so by becoming dormant, they need less extreme conditions to actually reproduce. I don't think the surface of Mars ever has conditions suitable for terrestrial life to reproduce, although somewhere underground theoretically could. --Tango (talk) 10:32, 12 September 2008 (UTC)[reply]
If there is never liquid water, coult sometning like a tardigrade live in the water ice layer a few inches below the Martian surface, dormant most of the time, but active and reproducing when conditions are least harsh? Desert plants and animals remain dormant for a year or longer on earth and use the rare less harsh conditions to do their business. Edison (talk) 18:55, 12 September 2008 (UTC)[reply]
Earth-derived life seems to requre exactly two things to flourish: liquid water, and an energy source. We've never found life where one or the other is missing, and everywhere we've looked that has both, we've found life. --Carnildo (talk) 21:35, 12 September 2008 (UTC)[reply]
If one is speculating about the forms that life might take, then there is no reason to suppose that water is a prerequisite for life to develop or exist. 196.2.124.253 (talk) 19:56, 12 September 2008 (UTC)[reply]
There is somewhat of a difference between lasting 10 years and 100000000 years between ice melting. Radiation damage would be far more severe, and any way what is there to eat for those tardigrades on Mars? The perchlorate would poison them anyway! Being animals they also need to respire oxygen . Graeme Bartlett (talk) 22:48, 12 September 2008 (UTC)[reply]
Gamma ray bursts are a very large release of energy. Assuming black holes have a limited lifetime because of an upper limit to the mass that they can contain, would an explosive release of that mass be of the same order of energy as observed gamma ray bursts? 196.2.124.253 (talk) 06:31, 12 September 2008 (UTC)[reply]
Since no existing theory predicts an upper limit to the mass of black holes, there's nothing we can really say about what would happen when a black hole hit such a limit. Algebraist09:46, 12 September 2008 (UTC)[reply]
Black holes don't explode... very small ones evaporate by Hawking radiation pretty explosively, but all black holes will evaporate at the same rate in their last X seconds of life, regardless of their starting mass (bigger ones will just take longer to get there). --Tango (talk) 10:30, 12 September 2008 (UTC)[reply]
This possibility has been explored by scientists, but not for black holes formed from stars since they last very very long, but for smaller black holes created in the big bang. I can't find any references but I think they studied what the signature flash would be like. No sightings so far. EverGreg (talk) 16:03, 12 September 2008 (UTC)[reply]
As far as I know, degeneracy pressure doesn't count for anything once it's collapsed into a black hole - there isn't really any matter left, there's just a singularity (of course, our understanding of black holes isn't really up to explaining what happens to the matter). Current theories don't include any kind of lower limit under which black holes explode, there's just Hawking radiation (which grows exponentially, so the last fraction of a second would seem rather explosive). --Tango (talk) 17:42, 12 September 2008 (UTC)[reply]
Radioactive decay in materials. Schrodinger's cat
The degree of decay in a given radioactive material is measured in half-life. If this is so, then surely it should be possible to predict the point in time at which a material has sufficiently decayed to an extent that it will trigger the release of a poisonous gas, thus killing an imprisoned cat? —Preceding unsigned comment added by 78.32.39.90 (talk) 08:13, 12 September 2008 (UTC)[reply]
Half-life is a measure of a quantity of atoms, i.e., statistical. No way to predict the behaviour of a single atom which is random. Those gedanken experiments you are referring to (see Schrödinger's cat) always involve a single atom, not a quantity. --Ayacop (talk) 08:30, 12 September 2008 (UTC)[reply]
The half-life is basically an average, there is plenty of deviation from that average for either small amounts of the isotope or small periods of time. --Tango (talk) 10:27, 12 September 2008 (UTC)[reply]
As the others say, the problem is that if it is a single atom you have no way of predicting when it will or won't decay. Half-life does not tell you about that. --98.217.8.46 (talk) 12:37, 12 September 2008 (UTC)[reply]
Instead of providing a solution, the statistical nature of half-life is actually what causes the problem. If you have a large quantity of a radioactive material, after one half life 50% of that material will have decayed. Therefore, there is a 50% probability that any individual atom in that material will decay. According to quantum mechanics, that atom actually exists in a superposition of states (decayed/radioactive) until we observe it, at which point our observation collapses the wave function into one state or other. The point of the schrodinger's cat thought experiment was that by including the cat in the system, the cat itself should be thought of as entagled with the atom and therefore as existing in a superposition of states (dead/alive) until we observe it, which is extremely counter-intuitive. Schrodigner originally meant the experiment as a discusison of QM's flaws, but subsequent interpretations of the thought experiment have been used to illustrate how other interpretations of QM operate. Read our article on it, it's not bad. --Shaggorama (talk) 14:18, 12 September 2008 (UTC)[reply]
Unsailable Dead Sea
Our Dead Sea article states that the "salinity makes for a harsh environment where animals cannot flourish and boats cannot sail". Why is that? Is it due to high buoyancy or the effect of the salt on the hull of the boats? Or something else? -- MacAddct 1984(talk • contribs)15:12, 12 September 2008 (UTC)[reply]
Animals not being able to flourish is certainly true (hence the name Dead Sea), but I can't see any reason why boats would have any difficulty, the added buoyancy should make things easier, not harder. --Tango (talk) 17:44, 12 September 2008 (UTC)[reply]
The very salty water might promote corrosion of metal hulls, but that's hardly the same as "boats cannot sail". --Anon, 22:06 UTC, September 12, 2008.
The Israel Museum certainly thinks it's possible to sail: [25] Now, they're just showing old anchors, so it's technically possible that all you can do is anchor a boat in the Dead Sea. ;) I would think though that the greater buoyancy would decrease draft and maybe make it much harder to control the boat. You might need so much ballast that your boat would be too heavy for the wind to push. Franamax (talk) 23:00, 12 September 2008 (UTC)[reply]
Electroforming solution
Is there anywhere where i can find some recipes for a coppor electrioforming solution. I know that the main components are distilled water, copper suphate and various acids but cannot find any information about quantaties of each. Any help would be very much appreciated.
regards
Kirk uk —Preceding unsigned comment added by 87.82.79.175 (talk) 16:04, 12 September 2008 (UTC)[reply]
I've knocking my knees every which way with a finger-long hammer (toy, tool? I know not which) and I'm getting no reflex. I've seen the graphics but can't find the spot. Argh. Imagine Reason (talk) 17:40, 12 September 2008 (UTC)[reply]
I think it's just below the knee cap, there's a soft bit. Make sure your knee is bent and you should feel a dip between the knee cap and the top of the lower leg bone (I'm sure someone will tell me what that bone is called, but I don't really care!). I can trigger the reflex by hitting that spot with the side of my hand. --Tango (talk) 17:46, 12 September 2008 (UTC)[reply]
Yes, the patellar tendon is the spot, like tango says (above the tibia). You can also try to enhance the reflex by clenching your teeth or trying to pull your clasped hands apart. Fribbler (talk) 17:49, 12 September 2008 (UTC)[reply]
I have been working in labs for a couple of years, but I never have understood exactly the qualifications for volumetric glassware to called class "A." Does anyone know what the requirements are? —Preceding unsigned comment added by 204.214.74.84 (talk) 18:12, 12 September 2008 (UTC)[reply]
I have read that article but I was wondering if there is a more precise definition of the classifications -- all the article says is that the graduation mark is placed more accurately. This begs the question, to what degree of accuracy? —Preceding unsigned comment added by 204.214.74.84 (talk) 19:55, 12 September 2008 (UTC)[reply]
Cost of Plug-in Hybrid Electric Vehicile (PHEV) vs. Internal Combustion Engine (ICE) in cents/mile?
Total lifetime operating cost of PHEV-vs-ICE, including the decrease in battery capacity and resistance to re-charge with time, as well as the difference in maintenace costs between PHEV and ICE technologies?
The Tennessee Valley Authority had a wind generator which charged battery powered vehicles as a demonstration project over 30 years ago, so clearly wind generated electricity could be used to charge the batteries of a plug-in hybrid vehicle. Any source of electricity could be used to charge any batteries, with varying cost effectiveness. As for the other question, experience may not exist yet for lifetime operating cost. What is the lifetime of a vehicle these days? Edison (talk) 01:06, 13 September 2008 (UTC)[reply]
angular momentum
Is angular momentum just a manifestation of linear momentum (ie you can treat angular momentum as the combination of thelinear momenta of each of the rotating object's particles)? There's a follow-up question. —Preceding unsigned comment added by 65.92.231.82 (talk) 21:04, 12 September 2008 (UTC)[reply]
Short answer, yes. I think it also works the other way around - linear momentum is just angular momentum taken around a point at infinity (don't quote me on that, though!). --Tango (talk) 21:25, 12 September 2008 (UTC)[reply]
This is probably a silly question -- I'm trying to make my quota for the week. If linear momentum is angular momentum taken around a point at infinity, is that point on the line of the linear motion, off to the right, downstage left, or?? Wanderer57 (talk) 21:46, 12 September 2008 (UTC)[reply]
I haven't heard this interpretation before, but it seems like it ought to be the point at infinity at right angles to the line (which of these two points you choose will just introduce a minus sign somewhere). Algebraist21:52, 12 September 2008 (UTC)[reply]
Wouldn't any point not on the line of motion yield a linear momentum? i.e. hold your reference point steady then allow the mass to continue moving, it's no longer at a right angle but the momentum is still linear. -- Mad031683 (talk) 22:03, 12 September 2008 (UTC)[reply]
Okay, there's a reason I asked this question. If I push against a vertical wall, I will gain linear momentum, right? But the earth in response will start spinning. Isn't the sum of the linear momenta of a rotating body equal to 0 (every point has corresponding point going in the opposite direction). So how is linear momentum conserved? Is the question even valid (a force is acting on each of the rotating particles to keep them in uniform circular motion)? —Preceding unsigned comment added by 65.92.231.82 (talk) 21:57, 12 September 2008 (UTC)[reply]
In considering the momentum changes when two bodies interact, you have to use a reference frame based on their common center of gravity. When the objects are you and the Earth, that will be near enough to the center of the Earth. When you push against a wall, you set the Earth spinning and you also set yourself rotating around that center of gravity. The momentum you gain only seems linear because your motion is constrained to be parallel to the Earth's surface and you move a small enough distance that the Earth seems flat. But angular momentum is conserved. --Anon, 22:17 UTC, September 12, 2008.
No. Gravity does not have to have to be intoduced. Besides, you can push strongly enought to surpass the earth's escape velocity. Anyway, even in your example linear momentum wouldn't be conserved. —Preceding unsigned comment added by 65.92.231.82 (talk) 23:26, 12 September 2008 (UTC)[reply]
Price is a factor: a TOW missile appears to have a unit cost (the missile, not the launcher) of $38,000. The M256 round an M1 Abrams MBT fires costs around $4000. The two rounds have comparable weight and lethality (although the TOW has greater range). That cheaper round means you can have more in inventory and thus don't have to be so careful in deciding what to shoot at (and so can shoot at lower-value targets). -- Finlay McWalter | Talk21:56, 12 September 2008 (UTC)[reply]
Yea, I've considered the costs. Missiles cost so much which is why railguns are so appealing in the future. But missiles can do things that cannons can't. Like being guided. Such a thing would be useful against attack helicopters and such. I would think that kind of extra protection would justify the extra costs. ScienceApe (talk) 22:14, 12 September 2008 (UTC)[reply]
It's always tempting (to generals in particular) to keep adding stuff on (until they've build an Apocalypse Tank). But you get much more flexibility if you build the antiaircraft capability separately, so you can a) defend what you like with it and b) it can be a mile or so behind the dynamic tank battle and still give effective AA protection. The jack of all trades is the (super expensive) master of none. -- Finlay McWalter | Talk22:33, 12 September 2008 (UTC)[reply]
Additionally, you don't really want all your big expensive fragile (and explosive) stuff outside the tank's armor. Even if its destruction won't harm the tank, it's highly vulnerable to soft kills and endangers exposed crew or nearby troops. — Lomn23:19, 12 September 2008 (UTC)[reply]
England MD/MBBS info
Hello every one.I need imformation about England Medical College/Universities for MD/MBBS courses.Please any body tell me the Tuition Fee,Living Fee,visa and other requirement for international students and also scholarship availibility.Any help will be much appreciated.OR someone wantto directly contact me are most wellcomed. thax —Preceding unsigned comment added by 202.125.143.76 (talk) 23:13, 12 September 2008 (UTC)[reply]
Unidentified Plant
File:UnkFlwr.jpg
Can you help me identify this plant? What I know: It has feathery light green leaves, 5 petal bloom with yellow centre, perennial, flowers are pink or white, grows tall, seems to spread easily, grows in southern Ontario.
Thanks, *Max* (talk) 00:09, 13 September 2008 (UTC).[reply]
F-16 Fuel consumption
Quoted from a local paper:
"Depending on thrust and altitude, an F-16 burns anywhere from 200 to 400 kilos of fuel a minute"
Yes, that's about right. You can google for "F-16 fuel consumption" to verify. There's an interesting table comparing the fuel consumption of different fighter variants. The consumption depends heavily on the mission, the payload at takeoff, the speed and altitude flown, etc. ~Amatulić (talk) 00:36, 13 September 2008 (UTC)[reply]
The table indicates a loiter time of 145 minutes, which would imply a fuel weight of at least (145 min)×(200 kg/min) = 29,000 kg or so, but F-16 indicates a dry weight of 8,670 kg and a maximum weight of 19,200 kg. I conclude, therefore, that the 200 kg/min figure is not actually a lower bound, and the burn rate could be a lot lower during cruise. Maybe 200-400 kg/min is a typical range, not an absolute range. -- Coneslayer (talk) 01:01, 13 September 2008 (UTC)[reply]
Kinetic energy revisited
Hi. Sorry if it looks like I'm being naïve again, but a few months ago I asked a question about kinetic energy, and I remember the following formula. This is not homework. kE=mv2; v=t•a; d=t2•a/2. Sorry I'm not good at LaTex, t= time, a= acceleration, d= distance. Anyway, here's the problem. An apple with a mass of 100g dropped from 1 metre has kE of roughly 1 joule. However, if I follow the distance formula, 1 = t2•5; t=~0.45, v=~4.47, kE=2. It should equal 1, so something isn't working. I'm not going to speculate by assuming that d=t2•a instead of d=t2•a/2, because that is probably wrong. Again, this is not homework, I would like to remind myself for myself. Thanks. ~AH1(TCU)00:29, 13 September 2008 (UTC)[reply]
Can you get salmonella from a turtle bite if you didn't bleed? The skin is starting to peel off, but I never started bleeding.
Thanks.
Nick (talk) 01:09, 13 September 2008 (UTC)nicholassayshi[reply]
^USDA/APHIS Environmental Assessment - In response to Monsanto Petition 06-178-01p seeking a Determination of Non-regulated Status for
+ Roundup RReady2Yield Soybean MON 89788, OECD Unique Identifier MON-89788-1, U.S. Department of Agriculture Animal and Plant Health Inspection Service
+ Biotechnology Regulatory Services page 13[27]
^National Agriculture Statistics Service (2005) in Acreage eds. Johanns, M. & Wiyatt, S. D. 6 30, (U.S. Dept. of Agriculture, Washington, DC).
+
^Impact of glyphosate-tolerant soybean and glufosinate-tolerant corn production on herbicide losses in surface runoff. Shipitalo MJ, Malone RW, Owens LB. J Environ Qual. 2008 37(2):401-8 PMID 18268303
Kettle
Teapot
.jpg){kind=link}
![[16]](https://en.wikipedia.org/wiki/Image:WorldMap_Voltage%26Frequency.png){kind=link}
![[23]](http://www.nature.com/nbt/journal/v18/n3/images/nbt0300_245a_I1.jpg){kind=link}
Thanks, *Max* (talk) 00:09, 13 September 2008 (UTC).
